SAP30BP (SAP30 binding protein) is a multifunctional nuclear protein that plays essential roles in both transcriptional regulation and pre-mRNA splicing. As a transcriptional regulator, SAP30BP functions through histone deacetylase-mediated mechanisms, inhibiting gene transcription by promoting histone deacetylation 1. In splicing regulation, SAP30BP serves as a critical cofactor for RBM17/SPF45-dependent splicing of short introns with truncated polypyrimidine tracts 2. The protein contains a UHM-ligand motif that directly binds to RBM17's UHM domain, facilitating RBM17 recruitment to phosphorylated SF3B1 in active spliceosomes 2. SAP30BP also interacts with other spliceosomal components and is associated with prespliceosomal complexes 3. Additionally, SAP30BP forms an essential complex with CDK11 and cyclin L, which is required for CDK11's regulatory function in spliceosome phosphorylation 4. Disease relevance includes associations with diabetic cardiomyopathy, where SAP30BP promotes ferroptosis through the MFN2-ACSL4 pathway 1, and potential protective effects against rotator cuff injuries 5. The protein's dual regulatory roles position it as an important coordinator linking transcriptional control with splicing machinery function.