PEPTIDE-SPECIFIC ANTIBODIES INDICATE SPECIES HETEROGENEITY OF A 42 KDA HIGH-AFFINITY INOSITOL 1,3,4,5-TETRAKISPHOSPHATE RECEPTOR PROTEIN FROM BRAIN

The aim of the present study was to identify a high affinity InsP(4) receptor in membranes from cerebellum or brain from several species. In samples obtained from sheep, beef human and rat, a 42 kDa protein represents an Ins(1,3,4,5)P-4 receptor, similar to the InsP(4) receptor from pig cerebellum, which we have described previously using an InsP(4)-photoaffinity analogue (Reiser et al., Biochem. J. 1991, 280, 533). CNBr cleavage of the pig receptor protein for peptide sequencing revealed peptide sequences which demonstrate that the 42 kDa InsP(4) receptor is a novel protein. Two synthetic peptides derived from the pig receptor were used to generate peptide-specific antisera which recognized also the intact receptor protein from pig. The two antisera showed different reactivity with the InsP(4) receptor purified from pig and human compared to sheep, beef and rat. This indicates a species heterogeneity of this protein. (C) 1995 Academic Press. Inc.