title: A variety of calpain/calpastatin systems in mammalian erythrocytes.
abstract: Calpain and its endogenous inhibitor, calpastatin, were isolated from erythrocytes of various mammals and their properties were compared. It has been widely believed that mammalian erythrocytes contain only mu-calpain. However, rat and human erythrocytes were found to contain two species of calpain, identified as mu-calpain and m-calpain from their elution positions on DEAE-cellulose column chromatography and their Ca(2+)-requirements. Thus, it is apparent that rat and human erythrocytes contain not only mu-calpain, but m-calpain as well. On the other hand, rabbit erythrocytes contain only mu-calpain. Western blot analysis showed that human and rabbit erythrocytes contain predominantly 70-kDa calpastatin (erythrocyte-type), but unnegligible amounts of 110-kDa calpastatin (tissue-type) are also present. Rat erythrocytes were shown to contain a calpastatin with a molecular mass of approx. 100 kDa almost exclusively; this molecular mass was in perfect coincidence with the mass of the calpastatin in rat lung. These results strongly suggest that rat erythrocytes contain a tissue-type calpastatin. No essential change in the calpain/calpastatin system during maturation of rabbit reticulocytes into mature erythrocytes was observed.
authors.affiliation: Department of Enzyme Biochemistry, Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inomata
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Imajoh-Ohmi
authors.forename: S
authors.initials: S
authors.lastname: Kawashima
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000097:blood* / Q000302:isolation & purification; D002154:Calpain / Q000097:blood* / Q000302:isolation & purification; D002454:Cell Differentiation / Q000502:physiology; D002848:Chromatography, DEAE-Cellulose; D004912:Erythrocytes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012156:Reticulocytes / Q000378:metabolism; D013045:Species Specificity
chemical_list: D002135:Calcium-Binding Proteins; C033668:calpastatin; D002154:Calpain