TSSK4

TSSK4, encoded by STK31, is the family member whose activity is directly switched on by another TSSK: TSSK6/SSTK phosphorylates its activation loop, establishing the only known kinase phosphorylation cascade inside the TSSK group. Although first described in germ cells, TSSK4 transcripts are detectable in a range of somatic tissues and are elevated in several cancers, including leukemia and glioma, where it may support proliferation. Like its siblings, TSSK4 possesses a CAMK-type catalytic domain but little is known about its physiological substrates. Recombinant TSSK4 produced with TSSK6 provides active enzyme for inhibitor screening and substrate discovery.