title: Biochemical and immunohistochemical evidence for a non-muscle myosin at the neuromuscular junction in bovine skeletal muscle.
abstract: We identified 220-kD protein in bovine skeletal muscle homogenate by affinity chromatography on an agarose column and subsequent SDS-PAGE. Peptide mass fingerprinting (MALDI mass spectrometry) and internal sequence analysis revealed that this protein has homology with several members of the myosin superfamily, particularly with human cardiac beta-myosin heavy chain (beta-MHC). A rabbit polyclonal antibody against the 220-kD protein specifically stained a 220-kD band in Western blots of skeletal muscle homogenate. Immunohistochemical experiments on cryostat sections demonstrated that in skeletal muscle this protein is exclusively localized at the neuromuscular junctions, no immunoreactivity being present at the myofibril level. Because of its relative homology with cardiac beta-MHC, we also investigated the distribution of the 220-kD protein in bovine heart. In cardiac fibers, 220-kD protein-related immunoreactivity was restricted to the intercalated disks, whereas myofibrils were completely devoid of specific immunoreactivity. This distribution pattern was completely different from that of cardiac beta-MHC, which involved myofibrils. Because of the above biochemical and immunohistochemical features, the 220-kD protein we have identified is suggested to be a novel member of the non-muscle (non-sarcomeric) myosin family.
authors.affiliation: Department of Cardiovascular Sciences, University La Sapienza, Rome, Italy. elena.pompili@uniroma1.it
authors.forename: Elena
authors.initials: E
authors.lastname: Pompili
authors.forename: Antonio
authors.initials: A
authors.lastname: De Luca
authors.forename: Stefania L
authors.initials: SL
authors.lastname: Nori
authors.forename: Bruno
authors.initials: B
authors.lastname: Maras
authors.forename: Gabriella
authors.initials: G
authors.lastname: De Renzis
authors.forename: Fulvia
authors.initials: F
authors.lastname: Ortolani
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Fumagalli
mesh_terms: D000818:Animals; D024722:Cardiac Myosins / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D007150:Immunohistochemistry; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D024462:Myosin Type II / Q000737:chemistry / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000378:metabolism*; D010449:Peptide Mapping; D011817:Rabbits; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid
chemical_list: D024722:Cardiac Myosins; D024462:Myosin Type II