Enables SH3 domain binding activity and identical protein binding activity. Involved in cell surface receptor signaling pathway; regulation of alternative mRNA splicing, via spliceosome; and spermatogenesis. Located in cytoplasm; membrane; and nucleus. Part of Grb2-Sos complex. Orthologous to human KHDRBS1 (KH RNA binding domain containing, signal transduction associated 1). [provided by Alliance of Genome Resources, Apr 2022]