Calvasculin, an encoded protein from mRNA termed pEL-98, 18A2, 42A, or p9Ka, is secreted by smooth muscle cells in culture and exhibits Ca(2+)-dependent binding to 36-kDa microfibril-associated glycoprotein.
Calvasculin, an EF-hand protein with a molecular mass of 11 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, is present abundantly in bovine aorta (Watanabe, Y., Kobayashi, R., Ishikawa, T., and Hidaka, H. (1992) Arch. Biochem. Biophys. 292, 563-569). This protein is synthesized constitutively by bovine aortic smooth muscle (BASM) cells and rat embryo fibroblast 3Y1 cells in culture. We discovered that calvasculin was secreted by BASM cells and 3Y1 cells. Immunofluorescence staining of BASM cells showed a granular distribution for calvasculin that was typical of a secreted protein. This protein bound with an extracellular matrix protein, 36-kDa microfibril-associated glycoprotein (36-kDa MAP), in a Ca(2+)-dependent manner in vitro. A stoichiometry analysis showed that the 36-kDa MAP bound 2.2 calvasculin eq/mol of protein. Solid-phase binding assays indicated a preferential affinity of native calvasculin for 36-kDa MAP among the extracellular matrices in a Ca(2+)-dependent manner. These results suggest that calvasculin, intracellular Ca(2+)-binding protein, is released to the extracellular space and binds with 36-kDa MAP.
Watanabe
Y
Y
Department of Pharmacology, Nagoya University, School of Medicine, Japan.
Usuda
N
N
Tsugane
S
S
Kobayashi
R
R
Hidaka
H
H
D000818:Animals; D001011:Aorta / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D000072260:RNA Splicing Factors; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins
D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D016326:Extracellular Matrix Proteins; D000072260:RNA Splicing Factors; D012333:RNA, Messenger; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C499413:S100A4 protein, Bos taurus; C016598:microfibrillar protein; D002118:Calcium