The Major Protein of Messenger Ribonucleoprotein Particles in Somatic Cells Is a Member of the Y-box Binding Transcription Factor Family

doi:10.1074/jbc.270.7.3186

The Major Protein of Messenger Ribonucleoprotein Particles in Somatic Cells Is a Member of the Y-box Binding Transcription Factor Family (*)

From the (1)Institute of Protein Research, Russian Academy of Sciences, Puschino, Moscow Region, Russian Federation and
(2)Department of Biological Chemistry, School of Medicine, University of California, Davis, California 95616

^§ To whom correspondence should be sent:
Dept. Biological Chemistry, UCD School of Medicine, Davis, CA 95616.
Tel.: 916-752-3235; Fax: 916-752-3516; jwhershey{at}ucdavis.edu

Abstract

A cDNA encoding the major core protein, p50, of cytoplasmic messenger ribonucleoprotein particles (mRNPs) of somatic cells was cloned from a rabbit reticulocyte cDNA library. From the derived 324-amino acid sequence, p50 is identified as a member of the Y-box binding transcription factor family. The protein was earlier described as a repressor of globin mRNA translation. These findings suggest that p50 may affect protein biosynthesis at two levels: mRNA transcription in the nucleus and mRNA translation in the cytoplasm. Together with recently published results showing that masked mRNA in germ cells also is associated with proteins of the Y-box binding protein family, the present finding indicates that these proteins are universal core proteins responsible for the formation of cytoplasmic mRNPs in eukaryotes. Highly purified p50 forms large 18 S homomultimeric complexes with a molecular mass of about 800 kilodaltons and melts RNA secondary structure. This suggests that p50 may affect translation by changing the overall structure of the mRNA.

Footnotes

↵* This work was supported by grants N 93-04-6548 from the Russian Fundamental Research Foundation, MUC000 from the International Science Foundation, a grant from the Russian State Programme “Cell-Free Protein Biosynthesis” (to L. P. O.), United States Public Health Service, National Institutes of Health Grant GM22135 (to J. W. B. H.), and National Science Foundation Grant MCB-91-23549 (to L. P. O. and J. W. B. H.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U16821[GenBank].
↵¹ The abbreviations used are:

mRNP

ribonucleoprotein particle

PABP

poly(A) binding protein

PAGE

polyacrylamide gel electrophoresis

HPLC

high performance liquid chromatography

PCR

polymerase chain reaction

IPTG

isopropyl-1-thio-β-D-galactopyranoside

bp

base pair(s)

kb

kilobase pair(s)

hnRPN

heterogeneous nuclear ribonucleoprotein particle.
- Received July 22, 1994.
- Revision received November 17, 1994.