Proteomic analysis identifies hnRNP L as a major nuclear Sam68-interacting protein. (A) LNCaP cell nuclear extracts were subjected to immunoprecipitation (IP) using anti-Sam68 rabbit antisera. IP was carried out in the presence or absence (+/-) of antisera to Sam68, with or without (+/-) Dynabeads Protein A, and either with or without (+/-) prior cross-linking of the antisera to the Dynabeads Protein A. Immunoprecipitates were resolved by SDS-PAGE, and six bands were excised from the Coomassie-stained gel for identification by peptide mass fingerprinting, of which 4 were positively identified. (B to E) MASCOT search results for Sam68-interacting proteins: Swiss-Prot entry names KHDR1_HUMAN (B: Sam68), ROA1_HUMAN (C: hnRNP A1), ROA2_HUMAN (C: hnRNP A2/B1), HNRPG_HUMAN (D: hnRNP G), and HNRPL_HUMAN (E: hnRNP L). Histograms show the MOWSE score distributions for identified peptides, with matched peptide sequences shown in bold red. The band corresponding to histogram (C) contained a mixture of peptides matching to Swiss-Prot entry names ROA1_HUMAN and ROA2_HUMAN.