| Type: | Family | Name: | U2 auxiliary factor small subunit |
| Description: | The U2 small nuclear ribonucleoprotein auxiliary factor (U2AF) is a heterodimeric splicing factor composed of a large and a small subunit. Thelarge U2AF subunit recognises the intronic polypyrimidine tract, a sequence located adjacent to the 3' splice site that serves as an importantsignal for both constitutive and regulated pre-mRNA splicing. The small subunit interacts with the 3' splice site dinucleotide AG and is essentialfor regulated splicing. The subunits shuttle continuously between the nucleus and the cytoplasm via a mechanism that involves carrier receptors and is independent of binding to mRNA. Both subunits contain an arginine/ serine-rich (RS) domain, which acts as a nuclear localisation signal.Furthermore, the presence of an RS domain on either subunit is sufficient to trigger the nucleocytoplasmic import of the heterodimeric complex.The human form of the U2 auxiliary factor small subunit, hU2AF35, contains a degenerate RNA recognition motif (RRM) and a C-terminal RS domain. Themurine form has been shown to be genomically imprinted with monoallelic expression from the paternal allele. However, this is not the case inhumans []. | Short Name: | U2_small |
