Recruited and tyrosine phosphorylated by several receptor systems, for example the T-cell, leptin and insulin receptors. Once phosphorylated, functions as an adapter protein in signal transduction cascades by binding to SH2 and SH3 domain-containing proteins. Role in G2-M progression in the cell cycle. Represses CBP-dependent transcriptional activation apparently by competing with other nuclear factors for binding to CBP. Also acts as a putative regulator of mRNA stability and/or translation rates and mediates mRNA nuclear export. Positively regulates the association of constitutive transport element (CTE)-containing mRNA with large polyribosomes and translation initiation. May not be involved in the nucleocytoplasmic export of unspliced (CTE)-containing RNA species. RNA-binding protein that plays a role in the regulation of alternative splicing and influences mRNA splice site selection and exon inclusion. Binds to RNA containing 5'-[AU]UAA-3' as a bipartite motif spaced by more than 15 nucleotides. Binds poly(A). Can regulate CD44 alternative splicing in a Ras pathway-dependent manner. In cooperation with HNRNPA1 modulates alternative splicing of BCL2L1 by promoting splicing toward isoform Bcl-X(S), and of SMN1. Can regulate alternative splicing of NRXN1 and NRXN3 in the laminin G-like domain 6 containing the evolutionary conserved neurexin alternative spliced segment 4 (AS4) involved in neurexin selective targeting to postsynaptic partners. In a neuronal activity-dependent manner cooperates synergistically with KHDRBS2/SLIM-1 in regulation of NRXN1 exon skipping at AS4. The cooperation with KHDRBS2/SLIM-1 is antagonistic for regulation of NXRN3 alternative splicing at AS4 (By similarity). Self-associates to form homooligomers when bound to RNA, oligomerization appears to be limited when binding to proteins. Interacts with KHDRBS3/SLIM-2 (By similarity). Interacts with KHDRBS2/SLIM-1; heterooligomer formation of KHDRBS family proteins may modulate RNA substrate specificity (PubMed:15345239). Interacts with PIK3R1, PLCG1 (PubMed:10437794, PubMed:10748127). Interacts with RASA1, GRB2, SRC, RBMY1A1, CBP, PRMT1, APC, HNRNPA1. Interacts with PTK6 (via SH3 and SH2 domains). Forms a complex with ILF2, ILF3, YLPM1, RBMX, NCOA5 and PPP1CA (By similarity). Binds WBP4/FBP21 (via WW domains), FNBP4/FBP30 (via WW domains). Interacts (via Arg/Gly-rich-flanked Pro-rich regions) with FYN (via the SH3 domain) (PubMed:10748127). Interacts with the non-receptor tyrosine kinase SRMS; the interaction leads to phosphorylation of KHDRBS1 (By similarity). Interacts with ZBTB7A; negatively regulates KHDRBS1 splicing activity toward BCL2L1 (By similarity). Predominantly located in the nucleus but also located partially in the cytoplasm. The KH domain is required for binding to RNA. The Pro-rich domains are flanked by Arg/Gly-rich motifs which can be asymmetric dimethylated on arginine residues to give the DMA/Gly-rich regions. Selective methylation on these motifs can modulate protein-protein interactions. Tyrosine phosphorylated by several non-receptor tyrosine kinases including LCK, FYN and JAK3. Also tyrosine phosphorylated by the non-receptor tyrosine kinase SRMS in an EGF-dependent manner. Phosphorylation by PTK6 negatively regulates its RNA binding ability. Phosphorylation by PTK6 at Tyr-440 dictates the nuclear localization of KHDRBS1. Acetylated. Positively correlates with ability to bind RNA (By similarity). Arginine methylation is required for nuclear localization, Inhibits interaction with Src-like SH3 domains, but not interaction with WW domains of WBP4/FBP21 AND FNBP4/FBP30. Belongs to the KHDRBS family.