García-Blanco M A, Jamison S F, Sharp P A
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Genes Dev. 1989 Dec;3(12A):1874-86. doi: 10.1101/gad.3.12a.1874.
A protein of molecular size 62,000 daltons (p62) was detected in HeLa cell nuclear extracts by UV cross-linking to mRNA precursors. p62 binds specifically to the polypyrimidine tract of the 3' splice site region of introns. p62 purified to homogeneity binds the polypyrimidine tract of pre-mRNAs. This binding does not require the AG dinucleotide at the 3' splice site. Alterations in the polypyrimidine tract that reduce the binding of p62 yield a corresponding reduction in the efficiency of formation of a U2 snRNP/pre-mRNA complex and splicing. The p62 protein is retained in the spliceosome, where it remains bound to the pre-mRNA. This polypyrimidine tract binding protein (pPTB) is proposed to be a critical component in recognition of the 3' splice site during splicing.
通过紫外线交联到mRNA前体，在HeLa细胞核提取物中检测到一种分子量为62,000道尔顿的蛋白质（p62）。p62特异性结合内含子3'剪接位点区域的多嘧啶序列。纯化至同质的p62结合前体mRNA的多嘧啶序列。这种结合不需要3'剪接位点处的AG二核苷酸。多嘧啶序列的改变降低了p62的结合，导致U2 snRNP/前体mRNA复合物形成效率和剪接相应降低。p62蛋白保留在剪接体中，在那里它仍然与前体mRNA结合。这种多嘧啶序列结合蛋白（pPTB）被认为是剪接过程中识别3'剪接位点的关键成分。
