※ TSSK family introduction

    TSSK (testis-specific serine kinase) belongs to CAMK group. Six members have been identified in this family in human genome.However, only five possess kinase catalytic domain including TSSK1, TSSK2, TSSK3, TSSK4 and TSSK6. TSSKs contain a kinase domain and a variable short C-terminal extension. All members contain a conserved activation loop threonine phosphorylation site. Two members TSSK2 and TSSK3 can undergo autophosphorylation. TSSK1 and TSSK2 are formed by tandem duplication and a dual knockout is infertile as a heterozygote. TSSK3 is expressed only in interstitial Leydig cells, which contrasts with the expression of TSSK1 and TSSK2 in late spermatids and sperm. TSSK4 can bind to CREB by Y2H and can phosphorylate and activate CREB in human and mouse cells (1).

Reference
1. Wikinome Annotation:    Kinase Family TSSK