Nebulette: a 107 kD nebulin-like protein in cardiac muscle.
A 107-kD protein has been identified in primary cultures of chicken embryonic cardiomyocytes by immunoprecipitations with certain anti-nebulin monoclonal antibodies (mAbs). These mAbs, prepared against a fragment of human skeletal muscle nebulin located near the carboxyl terminus, detect a 107-kD protein in extracts of adult chicken heart, adult mouse heart, and adult rabbit heart by immunoblot analysis. A partial cDNA corresponding to this protein has been isolated by immunological screening of a chicken heart cDNA expression vector library. The partial cDNA encodes a 380-amino acid open reading frame composed entirely of nebulin-like 35-residue modules marked by the highly conserved sequence motifs: SXXXYK and TPD. The open reading frame exhibits 60-85% homology with skeletal muscle nebulins from a variety of species. This cDNA recognizes an approximately 8-kb transcript in cardiac RNA and does not hybridize to skeletal muscle RNAs by northern analysis. Immunofluorescence localization of this nebulin-like protein in primary cultures of chicken cardiomyocytes and embryonic chicken cardiac myofibrils indicates that the protein is localized to the I-Z-I complex of the myofibrils, extending approximately 25% of the thin filament length. Comparisons of the distribution of this protein relative to actin, myosin, and titin in spreading cardiomyocytes suggest that the cardiac nebulin-like protein becomes aligned with the nascent myofibrils early during myofibrillogenesis. To distinguish this petite nebulin-like protein from the 600-900 kD skeletal muscle nebulin, we have named it nebulette.
Moncman
C L
CL
Department of Chemistry and Biochemistry, University of Texas, Austin 78712, USA.
Wang
K
K
D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001483:Base Sequence; D002352:Carrier Proteins; D002478:Cells, Cultured / Q000502:physiology; D002642:Chick Embryo; D003429:Cross Reactions; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary / Q000235:genetics; D015723:Gene Library; D005820:Genetic Testing; D006801:Humans; D015151:Immunoblotting; D060588:LIM Domain Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis* / Q000235:genetics* / Q000276:immunology; D018482:Muscle, Skeletal / Q000737:chemistry; D009206:Myocardium / Q000737:chemistry* / Q000166:cytology; D009210:Myofibrils / Q000737:chemistry; D011817:Rabbits; D012518:Sarcomeres / Q000737:chemistry; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D060588:LIM Domain Proteins; D009124:Muscle Proteins; C486890:NEBL protein, human; C486891:Nebl protein, mouse; C035620:nebulin