Intracellular localization of low and high calcium-requiring forms of calpain*.
Monospecific and discriminative antibodies against two distinct forms of calpain (Ca2+-dependent cysteine proteinase) were obtained. Immunological cross-reactivity between the heavy subunits of calpain I (low Ca2+-requiring form) and calpain II (high Ca2+-requiring form) were calculated to be 15 to 17%, and two steps of affinity chromatography was required to obtain discriminative antibodies. Using these antibodies, we have shown that a minor but reproducible amount of calpain I is associated with the membrane of human erthrocytes. Indirect immunofluorescent staining of cultured PK 15 cell revealed diffuse and finely granular cytoplasmic staining. Porcine kidney stained with either anti-calpain I IgG or anti-calpain II IgG yielded strong stainings in proximal and distal convoluted tubules, while glomerulus, macula densa and interstitial cells were not stained.
Murachi
T
T
Yoshimura
N
N
D000818:Animals; D000906:Antibodies; D000911:Antibodies, Monoclonal; D002118:Calcium / Q000494:pharmacology; D002154:Calpain; D010450:Endopeptidases / Q000032:analysis* / Q000097:blood; D004910:Erythrocyte Membrane / Q000201:enzymology; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight
D000906:Antibodies; D000911:Antibodies, Monoclonal; D046911:Macromolecular Substances; D010450:Endopeptidases; D002154:Calpain; D002118:Calcium