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Full-Text Articles in Cell Biology

Lattice Arrangement Of Myosin Filaments Correlates With Fiber Type In Rat Skeletal Muscle, Weikang Ma, Kyounghwan Lee, Shixin Yang, Thomas C. Irving, Roger Craig Dec 2019

Lattice Arrangement Of Myosin Filaments Correlates With Fiber Type In Rat Skeletal Muscle, Weikang Ma, Kyounghwan Lee, Shixin Yang, Thomas C. Irving, Roger Craig

Radiology Publications and Presentations

The thick (myosin-containing) filaments of vertebrate skeletal muscle are arranged in a hexagonal lattice, interleaved with an array of thin (actin-containing) filaments with which they interact to produce contraction. X-ray diffraction and EM have shown that there are two types of thick filament lattice. In the simple lattice, all filaments have the same orientation about their long axis, while in the superlattice, nearest neighbors have rotations differing by 0 degrees or 60 degrees . Tetrapods (amphibians, reptiles, birds, and mammals) typically have only a superlattice, while the simple lattice is confined to fish. We have performed x-ray diffraction and electron microscopy ...


Structural Organization Of The C1a-E-C Supercomplex Within The Ciliary Central Apparatus, Gang Fu, Lei Zhao, Erin Dymek, Yuqing Hou, Kangkang Song, Nhan Phan, Zhiguo Shang, Elizabeth F. Smith, George B. Witman, Daniela Nicastro Oct 2019

Structural Organization Of The C1a-E-C Supercomplex Within The Ciliary Central Apparatus, Gang Fu, Lei Zhao, Erin Dymek, Yuqing Hou, Kangkang Song, Nhan Phan, Zhiguo Shang, Elizabeth F. Smith, George B. Witman, Daniela Nicastro

Radiology Publications and Presentations

Nearly all motile cilia contain a central apparatus (CA) composed of two connected singlet microtubules with attached projections that play crucial roles in regulating ciliary motility. Defects in CA assembly usually result in motility-impaired or paralyzed cilia, which in humans causes disease. Despite their importance, the protein composition and functions of the CA projections are largely unknown. Here, we integrated biochemical and genetic approaches with cryo-electron tomography to compare the CA of wild-type Chlamydomonas with CA mutants. We identified a large ( > 2 MD) complex, the C1a-e-c supercomplex, that requires the PF16 protein for assembly and contains the CA components FAP76 ...


The Mammalian Linc Complex Regulates Genome Transcriptional Responses To Substrate Rigidity, Samer G. Alam, Qiao Zhang, Nripesh Prasad, Yuan Li, Srikar Chamala, Ram Kuchibhotla, Birendra Kc, Varun Aggarwal, Shristi Shrestha, Angela L. Jones, Shawn E. Levy, Kyle J. Roux, Jeffrey A. Nickerson, Tanmay P. Lele Dec 2016

The Mammalian Linc Complex Regulates Genome Transcriptional Responses To Substrate Rigidity, Samer G. Alam, Qiao Zhang, Nripesh Prasad, Yuan Li, Srikar Chamala, Ram Kuchibhotla, Birendra Kc, Varun Aggarwal, Shristi Shrestha, Angela L. Jones, Shawn E. Levy, Kyle J. Roux, Jeffrey A. Nickerson, Tanmay P. Lele

Open Access Articles

Mechanical integration of the nucleus with the extracellular matrix (ECM) is established by linkage between the cytoskeleton and the nucleus. This integration is hypothesized to mediate sensing of ECM rigidity, but parsing the function of nucleus-cytoskeleton linkage from other mechanisms has remained a central challenge. Here we took advantage of the fact that the LINC (linker of nucleoskeleton and cytoskeleton) complex is a known molecular linker of the nucleus to the cytoskeleton, and asked how it regulates the sensitivity of genome-wide transcription to substratum rigidity. We show that gene mechanosensitivity is preserved after LINC disruption, but reversed in direction. Combined ...


Dissection Of The Mitotic And Nuclear Functions Of Chromator, A Nuclear-Derived Spindle Matrix Component In Drosophila, Yun Ding Jan 2008

Dissection Of The Mitotic And Nuclear Functions Of Chromator, A Nuclear-Derived Spindle Matrix Component In Drosophila, Yun Ding

Retrospective Theses and Dissertations

A spindle matrix has long been proposed to serve as a stationary or elastic molecular matrix substrate for the organization and activities of microtubules and motors, based on the consideration of a mechanical and functional support for the stabilization of microtubule spindle during force generation from mitotic motors. Recently, the identification of four Drosophila proteins, Skeletor, Megator, EAST and Chromator has provided molecular evidence for the existence of this macromolecular matrix structure during mitosis. All of these four proteins have been shown to interact with each other within a protein complex and redistribute from the nucleus at interphase to form ...


Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao Jan 2008

Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao

Retrospective Theses and Dissertations

Epigenetic regulation is an important process utilized by biological systems to control gene expression and organize development, with histone modification enzymes among the most important components in this regulatory network. The predominant interphase H3 Serine10 kinase in Drosophila is JIL-1, which plays an important role in regulating chromosome structure and modulating gene expression. The full-length JIL-1 protein is composed of four domains including a N-terminal domain (NTD), two kinase domains (KDI and KDII), and a unique C-terminal domain (CTD). In order to study the biological importance of these individual domains, a domain analysis research approach was taken and different functions ...


Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay Jan 2007

Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay

Retrospective Theses and Dissertations

Cancer, which is characterized by uncontrolled cell division and proliferation, is the second leading cause of death in the United States. Of these deaths, approximately 30% are the result of mutations in Ras protein. When activated, Ras propagates multiple signal transduction cascades and induces cell proliferation, differentiation, and apoptosis. Within the Ras subfamily, there are several isoforms of Ras which differ in their posttranslational modifications. The modifications include proteolytic cleavage of the CAAX box, farnesylation, and palmitoylation which act as plasma membrane anchors where most signal transduction takes place. This dissertation demonstrates that Ras endocytosis takes place through a novel ...


Characterization Of Three Spindle Matrix Proteins, Megator, East And Asator, In Drosophila, Hongying Qi Jan 2007

Characterization Of Three Spindle Matrix Proteins, Megator, East And Asator, In Drosophila, Hongying Qi

Retrospective Theses and Dissertations

Two previously identified proteins Skeletor and Chromator provide the molecular evidence for the existence of a spindle matrix complex in Drosophila. The spindle matrix has been proposed to be a macromolecular complex, which plays a role in organization and stabilization of the mitotic spindle as well as in providing structural support for counterbalancing force production.;In this dissertation, I present the identification and characterization of three more putative spindle matrix candidate proteins, Megator, EAST and Asator. Megator, an ortholog of the mammalian TPR protein, contains a large coiled-coil domain at its NH2-terminus and an acidic, non-structural COOH-terminus. Immunohistochemistry studies show ...


Role Of Leu[Superscript B 10] In Cytoglobin And Comparison Of Direct And Indirect Measurements Of Hexacoordinate Hemoglobin Ligand Affinity, Jordan Richard Witmer Jan 2007

Role Of Leu[Superscript B 10] In Cytoglobin And Comparison Of Direct And Indirect Measurements Of Hexacoordinate Hemoglobin Ligand Affinity, Jordan Richard Witmer

Retrospective Theses and Dissertations

Hexacoordinate hemoglobins (HxHbs) have recently been discovered and have been found in nearly all living organisms. In humans, hxHbs are represented by neuroglobin (Ngb) and cytoglobin (Cgb). While Ngb is principally found in the brain, Cgb is ubiquitously expressed in all tissues. Ligand binding in hexacoordinate hemoglobins is complex due to the reversible coordination of the heme iron by the distal histidine. Hexacoordination regulates ligand binding and is regulated by specific residues in the heme pocket including the B10 position. Therefore, we investigated the influence of LeuB10 on hexacoordination and ligand binding in Cgb. Ligand binding was analyzed for recombinant ...


From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng Jan 2006

From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng

Retrospective Theses and Dissertations

Ras proteins are small G proteins that play key roles in many aspect of cell signal transduction. H-Ras is one of three isoforms of mammalian Ras protein that is best studied. The work presented in this dissertation describes how the carboxyl terminal lipid modifications affect the transportation, signal transduction and micro-localizations of H-Ras protein. The already known traffic pathway for H-Ras to the plasma membrane is Golgi mediated classical vesicular Transportation; However, we found the H-Ras transportation has many different features other than the classical pathway, and thereby discovered a new pathway for H-Ras targeting to the plasma membrane. This ...


Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath Jan 2005

Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath

Retrospective Theses and Dissertations

A spindle matrix is a macromolecular structure hypothesized to provide a stationary support or strut for the anchorage of motor proteins during force generation, microtubule sliding, and chromosome segregation in mitosis. Previous work in Drosophila has shown Skeletor, as the first putative molecular candidate of spindle matrix structure since it possesses many features consistent with the proposed spindle matrix structure.;We have identified two more putative spindle matrix candidate proteins, Chromator and Megator, using yeast two-hybrid interaction assay, cross-immunoprecipitation and immunocytochemistry. Chromator is a novel and essential chromodomain containing protein that interacts directly with Skeletor and extensively colocalizes with it ...


Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh Jan 2005

Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh

Retrospective Theses and Dissertations

Starch is one of the most abundant carbohydrates on earth serving vital roles as the primary energy reserve of plants, a significant source of calories in the human diet, and a renewable resource for other industrial applications. The multiplicity of starch biosynthetic enzymes is evolutionarily conserved in plants suggesting their functions are essential in starch biosynthesis. The overall goal of this research is to determine the specific molecular functions of the multiple starch branching enzyme (BE) isoforms in maize.;This dissertation first addresses what, if any, are the differences in enzymatic properties of BEIIa and BEIIb. Two polyclonal antisera were ...


The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang Jan 2004

The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang

Retrospective Theses and Dissertations

JIL-1 encodes a chromatin-associated tandem serine/threonine kinase in Drosophila melanogaster. JIL-1 predominantly associates with interbands on polytene chromosomes. It appears at higher levels on the X chromosome than on autosomes in males, and distributes about equally on all chromosomes in females. In addition, in males JIL-1 overlaps with the MSL (for male specific lethal) complex that specifically associates with the male X chromosome on which expression of most genes are upregulated.;We isolated JIL-1 mutants by inducing imprecise excision of an EP element inserted in JIL-1. We found that JIL-1 is required for viability of both females and males ...


Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani Jan 2004

Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani

Retrospective Theses and Dissertations

This thesis describes the structural and molecular analysis of two leech neuronal proteins, Calsensin and Filamin. Calsensin is an EF-hand calcium-binding protein expressed by a subset of peripheral sensory neurons which fasciculate into a single tract in the leech central nervous system. Calsensin is a 9 kD protein with two EF-hand calcium-binding motifs. Calsensin can multimerize via disulfide bridge formation involving the two cysteine residues in vitro. Furthermore, Calsensin shows differential gel migration depending on the presence or absence of calcium suggesting a conformational change upon calcium binding. Using multidimensional NMR spectroscopy we have determined the solution structure and backbone ...


Mechanism For Membrane Electroporation Irreversibility Under High-Intensity, Ultrashort Electrical Pulse Conditions, R. P. Joshi, K. H. Schoenbach Jan 2002

Mechanism For Membrane Electroporation Irreversibility Under High-Intensity, Ultrashort Electrical Pulse Conditions, R. P. Joshi, K. H. Schoenbach

Bioelectrics Publications

An improved electroporation model is used to address membrane irreversibility under ultrashort electric pulse conditions. It is shown that membranes can survive a strong electric pulse and recover provided the pore distribution has a relatively large spread. If, however, the population consists predominantly of larger radii pores, then irreversibility can result. Physically, such a distribution could arise if pores at adjacent sites coalesce. The requirement of close proximity among the pore sites is more easily satisfied in smaller organelles than in outer cell membranes. Model predictions are in keeping with recent observations of cell damage to intracellular organelles (e.g ...


Theoretical Predictions Of Electromechanical Deformation Of Cells Subjected To High Voltages For Membrane Electroporation, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson Jan 2002

Theoretical Predictions Of Electromechanical Deformation Of Cells Subjected To High Voltages For Membrane Electroporation, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

An electromechanical analysis based on thin-shell theory is presented to analyze cell shape changes in response to external electric fields. This approach can be extended to include osmotic-pressure changes. Our calculations demonstrate that at large fields, the spherical cell geometry can be significantly modified, and even ellipsoidal forms would be inappropriate to account for the deformation. Values of the surface forces obtained from our calculations are in very good agreement with the 1–10 mN/m range for membrane rupture reported in the literature. The results, in keeping with reports in the literature, demonstrate that the final shape depends on ...


The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden Jan 2000

The Contributions Of The Hras C-Terminus And Its Lipid Modifications To Hras Signal Transduction Events And Membrane Binding , Michelle Ann Booden

Retrospective Theses and Dissertations

In the GTP bound state, Ras proteins activate multiple downstream effector proteins, the combination of which regulate cell growth, differentiation, and changes in cell shape. However, Ras proteins must undergo C-terminal lipidation before they can support biological activity. Specifically, the C-terminus of the HRas protein must be modified by a farnesyl at Cys186 and two palmitates at Cys181 and Cys184. The current paradigm suggests that palmitate is not attached without prior farnesyl addition and that these post-translational lipid modifications are only necessary for membrane association. However, emerging evidence suggests that the C-terminus and its lipid modifications may also be responsible ...


Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney Jan 2000

Mechanisms Of Negative Regulation Of Protein Prenylation: Investigation Of Murine Guanylate-Binding Protein 1 , John Thomas Stickney

Retrospective Theses and Dissertations

Covalent attachment of isoprenoid lipids to proteins is a post-translational modification that occurs on approximately 2% of all cellular proteins. Proteins that contain a CaaX motif as their final four amino acids are presumed to be targets for the addition of C15 or C20 isoprenoids by farnesyl transferase (FTase) or geranylgeranyl transferase I (GGTase I) respectively. This modification is generally believed to occur stoichiometrically, and irreversibly, in vivo. Thus, if prenylation is to be regulated, this control must occur prior to lipid addition. At the moment, there is little evidence that the enzymatic activity of prenyl transferases can be modulated ...


Effects Of Altering Titin Expression On Myofibril Assembly In A Skeletal Muscle Cell Line , Qunfeng Dong Jan 2000

Effects Of Altering Titin Expression On Myofibril Assembly In A Skeletal Muscle Cell Line , Qunfeng Dong

Retrospective Theses and Dissertations

Titin is a giant muscle protein that spans the distance from the Z line to the M line in sarcomeres of striated muscle myofibrils. One of the functions proposed for titin is that it could act as a molecular scaffold to direct sarcomere assembly. To investigate this role of titin, titin expression was transiently altered in the cultured mouse skeletal muscle cell line C2C12 by either a dominant-negative approach or an antisense mRNA approach. The time course of myofibril assembly was monitored by immunofluorescence labeling with antibodies to actin, alpha-actinin, titin, and myosin from 1 to 5 d after myoblast ...


Fatty Acid Modification Of Cells In Culture By Overexpression Of Exogenous Desaturases , Travis Jay Knight Jan 1999

Fatty Acid Modification Of Cells In Culture By Overexpression Of Exogenous Desaturases , Travis Jay Knight

Retrospective Theses and Dissertations

COS-1 cells were transfected transiently with expression vectors encoding stearoyl-acyl-carrier-protein desaturase (SACPD) from castor bean, stearoyl-CoA desaturase (SCD) from mice, and a control vector containing SACPD cDNA in reverse orientation. The hypothesis was that both exogenous desaturases would be active in COS-1 cells, thereby increasing the proportion of monounsaturated fatty acids produced by the cells. Messenger RNA and anti-myc immunoreactive proteins were detected at 12 and 24 hours post-transfection respectively and increased through 48 hours post-transfection. When acetate was used as the fatty acid precursor in cultures for a 24-hour period starting 24 hours post-transfection, the ratio of monounsaturated to ...


Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe Dec 1993

Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe

Electronic Theses and Dissertations

The L2Hs sequences are a polymorphic, interspersed, middle repetitive DNA family unique to human genomes. Genomic fingerprinting indicates that these DNAs vary from one individual to another and between tissues of the same individual. Sequence analysis reveals that they are AT-rich (76%) and contain many unusual sequence arrangements (palindromes, inverted and direct repeats). These sequence properties confer on the L2Hs elements the potential to fold into non-B-form structures, a characteristic of recombination hot spots. To test this hypothesis carbodiimide, osmium tetroxide and S$\sb1$ nuclease were used as single-strand specific probes to study a recombinant plasmid, pN6.4.39, containing ...


Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick Aug 1991

Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick

Electronic Theses and Dissertations

Analysis of E. coli strains SK1047 and SK1048 have shown them to be temperature-sensitive, protein-synthesis deficient. An alteration in ribosomal protein L22 was detected in both strains using two dimensional gel electrophoresis. Protein L22 was purified from both strains by reversed phase high performance liquid chromatography and from two dimensional electrophoretic gels. Purified ribosomal protein L22 was labeled by reductive methylation and used in 23S RNA binding assays with and without ribosomal protein L4. At the permissive temperature, protein L22 from SK1047 bound less efficiently than the control while protein L22 from SK1048 bound as efficiently as the control. At ...