This family consists of several eukaryotic SH3 domain-binding protein 5 or c-Jun N-terminal kinase (JNK)-interacting proteins (SH3BP5 or Sab). Sab binds to and serves as a substrate for JNK in vitro, and has been found to interact with the Src homology 3 (SH3) domain of Bruton's tyrosine kinase (Btk). Inspection of the sequence of Sab reveals the presence of two putative mitogen-activated protein kinase interaction motifs (KIMs) similar to that found in the JNK docking domain of the c-Jun transcription factor, and four potential serine-proline JNK phosphorylation sites in the C-terminal half of the molecule [1].

1: A new c-Jun N-terminal kinase (JNK)-interacting protein, Sab (SH3BP5), associates with mitochondria. Wiltshire C, Matsushita M, Tsukada S, Gillespie DA, May GH; Biochem J 2002;367:577-585. PMID:12167088