Localization of Ca(2+)-binding proteins of rat cortex on two-dimensional gels-II. analysis of Ca(2+) binding proteins in ammonium sulfate fractions of rat brain.

A total of seven high-affinity calcium-binding proteins have been detected in rat brain. This was accomplished using a combination of ammonium sulfate fractionation, two-dimensional gel electrophoresis, western blotting and (45)Ca(2+)-autoradiography. Of these seven proteins, three are detectable in a crude tissue punch of rat cortex while four are seen only after protein enrichment with ammonium sulfate. Four of the seven proteins detected in this study have been identified: calmodulin, the B subunit of calcineurin, the intestinal vitamin D-dependent calcium-binding protein and parvalbumin. The identities of the other three proteins visualized by (45)Ca(2+)-autoradiography in this study are unknown.