Identification and purification of a 62,000-dalton protein that binds specifically to the polypyrimidine tract of introns.
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.
García-Blanco
M A
MA
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Jamison
S F
SF
Sharp
P A
PA
D001483:Base Sequence; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011743:Pyrimidines / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D015183:Restriction Mapping; D012261:Ribonucleoproteins / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear
D002352:Carrier Proteins; D011743:Pyrimidines; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear