U1-specific protein C needed for efficient complex formation of U1 snRNP with a 5' splice site.
One of the functions of U1 small nuclear ribonucleoprotein (snRNP) in the splicing reaction of pre-mRNA molecules is the recognition of the 5' splice site. U1 snRNP proteins as well as base-pair interactions between U1 snRNA and the 5' splice site are important for the formation of the snRNP-pre-mRNA complex. To determine which proteins are needed for complex formation, the ability of U1 snRNPs gradually depleted of the U1-specific proteins C, A, and 70k to bind to an RNA molecule containing a 5' splice site sequence was studied in a nitrocellulose filter binding assay. The most significant effect was always observed when protein C was removed, either alone or together with other U1-specific proteins; the binding was reduced by 50 to 60%. Complementation of protein C-deficient U1 snRNPs with purified C protein restored their 5' splice site binding activity. These data suggest that protein C may potentiate the base-pair interaction between U1 RNA and the 5' splice site.
Heinrichs
V
V
Institut fuer Molekularbiologie und Tumorforschung, Marburg, Federal Republic of Germany.
Bach
M
M
Winkelmann
G
G
Lührmann
R
R
D000818:Animals; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D007438:Introns; D012326:RNA Splicing; D012261:Ribonucleoproteins / Q000235:genetics / Q000502:physiology*; D017411:Ribonucleoproteins, Small Nuclear
D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear