Analysis of the expression, localization and activity of rat casein kinase Iε-3

Casein kinase Iepsilon (CKIepsilon) is a serine/threonine protein kinase that has been suggested to participate in the regulation of various signaling pathways. In this report, we examined the tissue distributions of three putative alternatively spliced forms of rCkIepsilon by RT-PCR. This analysis confirmed that all three isoforms are expressed in rat tissues with different tissue-specific expression patterns. Immunohistochemical analysis showed that the intracellular distribution of rCKIepsilon-3 in neurons was broader than that of rCKIepsilon-1. Moreover, the kinase activity of the rCKIepsilon-3 protein differed from that of rCKIepsilon-1. These data suggest that rCKIepsilon-1 and rCKIepsilon-3 may play different functional roles.