Eukaryotic mRNA cap binding protein: purification by affinity chromatography on sepharose-coupled m7GDP.

Abstract
A 24,000-dalton polypeptide that binds strongly and can be specifically crosslinked to the 5''-terminal cap structure m7GpppN in eukaryotic mRNA was detected in protein synthesis initiation factor preparations. This polypeptide was purified to apparent homogeneity by 1 chromatographic passage through an affinity resin prepared by coupling the levulinic acid O2'',3''-acetal of m7GDP to AH-Sepharose 4B. Translation, in HeLa [human cervical carcinoma] cell extracts, of capped mRNA including Sindbis virus, reovirus and rabbit globin mRNA was stimulated by the cap-binding protein under conditions that did not increase translation of noncapped RNA of encephalomyocarditis virus and satellite tobacco necrosis virus.