title: Calmodulin and rat vitamin D-dependent calcium-binding proteins: biochemical and immunochemical comparison.
abstract: Purified vitamin D-dependent rat intestinal (Mr 10,000) and rat renal (Mr 28,000) calcium-binding proteins (CaBPs) have been compared to vertebrate calmodulin, and the vitamin D-dependent CaBPs have been found to be distinct from calmodulin by biochemical and immunochemical criteria. Rat renal and rat intestinal CaBPs do not stimulate 3',5'-cyclic nucleotide phosphodiesterase, do not compete with iodinated calmodulin for binding to phenothiazine-Sepharose conjugates, do not cross-react immunochemically, and do not contain N epsilon-trimethyllysine. In addition, although calmodulin exhibits a characteristic calcium-dependent mobility shift on polyacrylamide gels in the presence of sodium dodecyl sulfate, a similar mobility shift is not observed for the vitamin D-dependent CaBPs. Immunocytochemically, calmodulin has a widespread localization in the kidney, whereas CaBP is present specifically in the distal tubules of the kidney. These localizations suggest a specialized role for CaBP in the kidney. Thus, although the vitamin D-dependent CaBPs and calmodulin are similar in that they are small, acidic, calcium-binding proteins, these two classes of proteins are biochemically and immunochemically distinct.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D002645:Chickens; D004789:Enzyme Activation; D007120:Immunochemistry; D007124:Immunoenzyme Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D010640:Phenothiazines / Q000378:metabolism; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D010640:Phenothiazines; D064030:S100 Calcium Binding Protein G; D015105:3',5'-Cyclic-AMP Phosphodiesterases