Purification and characterization of beta-adrenergic receptor mRNA-binding proteins.
Beta-adrenergic receptors (beta-ARs), like other G-protein-coupled receptors, can undergo post-transciptional regulation at the level of mRNA stability. In particular, the human beta(1)- and beta(2)-ARs and the hamster beta(2)-AR mRNA undergo beta-agonist-mediated destabilization. By UV cross-linking, we have previously described an approximately M(r) 36,000 mRNA-binding protein, betaARB, that binds to A/C+U-rich nucleotide regions within 3'-untranslated regions. Further, we have demonstrated previously that betaARB is immunologically distinct from AUF1/heterogeneous nuclear ribonucleoprotein (hnRNP) D, another mRNA-binding protein associated with destabilization of A+U-rich mRNAs (Pende, A., Tremmel, K. D., DeMaria, C. T., Blaxall, B. C., Minobe, W., Sherman, J. A., Bisognano, J., Bristow, M. R., Brewer, G., and Port, J. D. (1996) J. Biol. Chem. 271, 8493-8501). In this report, we describe the peptide composition of betaARB. Mass spectrometric analysis of an approximately M(r) 36,000 band isolated from ribosomal salt wash proteins revealed the presence of two mRNA-binding proteins, hnRNP A1, and the elav-like protein, HuR, both of which are known to bind to A+U-rich nucleotide regions. By immunoprecipitation, HuR appears to be the biologically dominant RNA binding component of betaARB. Although hnRNP A1 and HuR can both be immunoprecipitated from ribosomal salt wash proteins, the composition of betaARB (HuR alone versus HuR and hnRNP A1) appears to be dependent on the mRNA probe used. The exact role of HuR and hnRNP A1 in the regulation of beta-AR mRNA stability remains to be determined.
Blaxall
B C
BC
Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Pellett
A C
AC
Wu
S C
SC
Pende
A
A
Port
J D
JD
D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface; D001483:Base Sequence; D002846:Chromatography, Affinity; D006224:Cricetinae; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000737:chemistry*; D016601:RNA-Binding Proteins / Q000737:chemistry*; D011943:Receptors, Adrenergic, beta / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry; D012261:Ribonucleoproteins / Q000737:chemistry; D014407:Tumor Cells, Cultured
D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011943:Receptors, Adrenergic, beta; D011994:Recombinant Proteins; D012261:Ribonucleoproteins