SAP18

Histone acetylation plays a key role in the regulation of eukaryotic gene expression. Histone acetylation and deacetylation are catalyzed by multisubunit complexes. The protein encoded by this gene is a component of the histone deacetylase complex, which includes SIN3, SAP30, HDAC1, HDAC2, RbAp46, RbAp48, and other polypeptides. This protein directly interacts with SIN3 and enhances SIN3-mediated transcriptional repression when tethered to the promoter. A pseudogene has been identified on chromosome 2. [provided by RefSeq]

Full Name

Sin3A-associated protein, 18kDa

Function

Component of the SIN3-repressing complex. Enhances the ability of SIN3-HDAC1-mediated transcriptional repression. When tethered to the promoter, it can direct the formation of a repressive complex to core histone proteins. Auxiliary component of the splicing-dependent multiprotein exon junction complex (EJC) deposited at splice junction on mRNAs. The EJC is a dynamic structure consisting of core proteins and several peripheral nuclear and cytoplasmic associated factors that join the complex only transiently either during EJC assembly or during subsequent mRNA metabolism. Component of the ASAP and PSAP complexes which bind RNA in a sequence-independent manner and are proposed to be recruited to the EJC prior to or during the splicing process and to regulate specific excision of introns in specific transcription subsets. The ASAP complex can inhibit mRNA processing during in vitro splicing reactions. The ASAP complex promotes apoptosis and is disassembled after induction of apoptosis. Involved in the splicing modulation of BCL2L1/Bcl-X (and probably other apoptotic genes); specifically inhibits the formation of proapoptotic isoforms such as Bcl-X(S); the activity is different from the established EJC assembly and function.

Biological Process

Biological Process mRNA processingIEA:UniProtKB-KW
Biological Process negative regulation of DNA-templated transcriptionManual Assertion Based On ExperimentIBA:GO_Central
Biological Process negative regulation of mRNA splicing, via spliceosomeManual Assertion Based On ExperimentIDA:UniProtKB
Biological Process positive regulation of apoptotic processManual Assertion Based On ExperimentIDA:UniProtKB
Biological Process regulation of alternative mRNA splicing, via spliceosomeManual Assertion Based On ExperimentIDA:UniProtKB
Biological Process regulation of transcription by RNA polymerase IIManual Assertion Based On ExperimentTAS:ProtInc
Biological Process RNA splicingIEA:UniProtKB-KW

Cellular Location

Nucleus
Cytoplasm
Nucleus speckle
Shuttles between the nucleus and the cytoplasm (PubMed:16314458).
Colocalizes with ACIN1 and SRSF2 in nuclear speckles (PubMed:20966198).