Caenorhabditis elegans UNC-96 is a new component of M-lines that interacts with UNC-98 and paramyosin and is required in adult muscle for assembly and/or maintenance of thick filaments.
To gain further insight into the molecular architecture, assembly, and maintenance of the sarcomere, we have carried out a molecular analysis of the UNC-96 protein in the muscle of Caenorhabditis elegans. By polarized light microscopy of body wall muscle, unc-96 mutants display reduced myofibrillar organization and characteristic birefringent "needles." By immunofluorescent staining of known myofibril components, unc-96 mutants show major defects in the organization of M-lines and in the localization of a major thick filament component, paramyosin. In unc-96 mutants, the birefringent needles, which contain both UNC-98 and paramyosin, can be suppressed by starvation or by exposure to reduced temperature. UNC-96 is a novel approximately 47-kDa polypeptide that has no recognizable domains. Antibodies generated to UNC-96 localize the protein to the M-line, a region of the sarcomere in which thick filaments are cross-linked. By genetic and biochemical criteria, UNC-96 interacts with UNC-98, a previously described component of M-lines, and paramyosin. Additionally, UNC-96 copurifies with native thick filaments. A model is presented in which UNC-96 is required in adult muscle to promote thick filament assembly and/or maintenance.
Mercer
Kristina B
KB
Department of Pathology, Emory University, Atlanta, GA 30322, USA.
Miller
Rachel K
RK
Tinley
Tina L
TL
Sheth
Seema
S
Qadota
Hiroshi
H
Benian
Guy M
GM
D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017238:Genes, Helminth / Q000235:genetics; D008969:Molecular Sequence Data; D009068:Movement / Q000502:physiology; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D009132:Muscles / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D009154:Mutation / Q000235:genetics; D009210:Myofibrils / Q000648:ultrastructure; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013696:Temperature; D014335:Tropomyosin / Q000378:metabolism*
D000906:Antibodies; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D009124:Muscle Proteins; D010455:Peptides; D020033:Protein Isoforms; D014335:Tropomyosin; C514106:UNC-96 protein, C elegans; C481656:UNC-98 protein, C elegans