New PKCδ family members, PKCδIV, δV, δVI, and δVII are specifically expressed in mouse testis

We isolated and characterized four new PKCδ isoforms, PKCδIV, δV, δVI, and δVII, specifically expressed in the mouse testis. These isoforms possess neither V1 nor C2-like domains. Moreover, PKCδVI and δVII have a different last exon as their V5 domain. The transcription of PKCδIV, δV, δVI, and δVII is initiated from the same site in the upstream region of exon4 of the PKCδ gene. They are expressed exclusively in the testis in an age-dependent manner. PKCδIV and δV are expressed in spermatids with sperm maturation stage-specific manner, and that PKCδVI and δVII are expressed in spermatogonia and spermatocytes.