Chemical cross-linking of Sm and RNP antigenic proteins.
Nuclear extracts, competent for in vitro premessenger RNA splicing, were chemically cross-linked with thiol-reversible reagents in order to study the organization of proteins within ribonucleoprotein particles (RNPs) containing uridine-rich small nuclear RNAs (UsnRNPs). The distribution of select UsnRNP antigens within cross-linked complexes was determined by Western blotting of diagonal two-dimensional gels. On the basis of calculations from the molecular weights of cross-linked complexes containing UsnRNP common proteins B', B, and D, it is proposed that each of these proteins was associated with UsnRNP common proteins E and G. In addition, D' is proposed to be positioned close to D. The spatial distribution of UsnRNP common proteins was such that B' and B could not be cross-linked to D. The data also suggested that the 63-kDa U1 snRNP specific protein was cross-linked to other U1-specific proteins, particularly C, but not to the UsnRNP common proteins. We propose that part of the UsnRNP core of common proteins contains at least two asymmetrical copies of B':B:D:D':E:G with stoichiometries of 2:1:1:1:1:1 and 1:2:1:1:1:1.
Harris
S G
SG
Department of Pathology and Laboratory Medicine, University of Rochester, New York 14642.
Hoch
S O
SO
Smith
H C
HC
D002467:Cell Nucleus / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D007096:Imidoesters / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight; D012322:RNA Precursors / Q000302:isolation & purification / Q000378:metabolism*; D012326:RNA Splicing; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear
D003432:Cross-Linking Reagents; D007096:Imidoesters; D012322:RNA Precursors; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; C007471:dimethyl dithiobispropionimidate