NKF1

Novel kinase family 1 gathers the SH3-binding kinases SBK1, SBK2 (SgK069) and SBK3 (SgK110), a set of relatives that could not be placed in any major kinome group when the classification was built. Each combines a protein kinase domain with regions that interact with SH3-containing proteins, but validated substrates have not been established for any member. Expression is tissue-restricted rather than ubiquitous, and reported observations concern roles in proliferation and in stress responses, mostly from overexpression or knockdown experiments. The family therefore remains an orphan cluster of the kinome, and recombinant NKF1 proteins are used chiefly to raise isoform-specific antibodies and to profile small-molecule selectivity.