Immunochemical evidence that myosin I heavy chain-like protein is identical to the 110-kilodalton brush-border protein.
In a previous study, we identified a new mammalian myosin heavy chain, termed myosin I heavy chain-like protein (MIHC), by molecular cloning of a bovine intestinal cDNA clone. In this investigation, we examined the relationship between MIHC and the 110-kDa intestinal brush-border protein, which possesses a myosin-like ATPase activity. We raised antibodies against a chemically synthesized oligopeptide representing a part of the MIHC sequence. These antibodies reacted specifically in immunoblots with the 110-kDa protein in both purified 110-kDa protein-calmodulin complex and crude microvillar protein extracts. Staining of tissue sections with these antibodies was specifically localized to the brush-border microvilli of small intestines, indicating an identical cellular localization for both MIHC and the 110-kDa protein. Furthermore, analysis of the MIHC sequence revealed two putative calmodulin-binding sites, which is consistent with the fact that the 110-kDa protein forms a complex with calmodulin. These results strongly support the conclusion that MIHC is identical to the 110-kDa protein and suggest that not only the conventional myosin system but also the MIHC (110-kDa protein)-calmodulin complex may play an important role in ATP-dependent and Ca2+-induced brush-border contraction.
Hoshimaru
M
M
Institute for Immunology, Kyoto University Faculty of Medicine.
Fujio
Y
Y
Sobue
K
K
Sugimoto
T
T
Nakanishi
S
S
D000048:Acanthamoeba; D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002645:Chickens; D007106:Immune Sera / Q000276:immunology; D015151:Immunoblotting; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D018995:Myosin Heavy Chains; D024461:Myosin Type I; D011506:Proteins / Q000276:immunology*; D013329:Structure-Activity Relationship
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D007106:Immune Sera; C062291:MYO1A protein, human; D011506:Proteins; D024461:Myosin Type I; D018995:Myosin Heavy Chains