We have reported here the biochemical characterization of a newly identified microfibril-associated protein of 36-kDa (36-kDa MAP) from bovine aorta. Using Ca2+-dependent affinity chromatography on an isoquinolinesulfonamide derivative (CKA-1303)-coupled Sepharose, we obtained a pure form of 36-kDa MAP. This compound should serve as a useful tool for clarifying the physiological roles of 36-kDa MAP. In addition, 45Ca-autoradiography clearly indicated that 36-kDa MAP binds Ca2+. Partial amino acid sequence of 36-kDa MAP was determined. Our search of that published sequence against a 36-kDa MAP sequence revealed the resemblance to fibrinogen-related proteins of sea cucumber, cytotactin and tenascin which are substrate-adhesion proteins made at critical stages of histogenesis. © 1994 Academic Press, Inc.