Purification, characterization, and cDNA cloning of an AU-rich element RNA-binding protein, AUF1.
The degradation of some proto-oncogene and lymphokine mRNAs is controlled in part by an AU-rich element (ARE) in the 3' untranslated region. It was shown previously (G. Brewer, Mol. Cell. Biol. 11:2460-2466, 1991) that two polypeptides (37 and 40 kDa) copurified with fractions of a 130,000 x g postribosomal supernatant (S130) from K562 cells that selectively accelerated degradation of c-myc mRNA in a cell-free decay system. These polypeptides bound specifically to the c-myc and granulocyte-macrophage colony-stimulating factor 3' UTRs, suggesting they are in part responsible for selective mRNA degradation. In the present work, we have purified the RNA-binding component of this mRNA degradation activity, which we refer to as AUF1. Using antisera specific for these polypeptides, we demonstrate that the 37- and 40-kDa polypeptides are immunologically cross-reactive and that both polypeptides are phosphorylated and can be found in a complex(s) with other polypeptides. Immunologically related polypeptides are found in both the nucleus and the cytoplasm. The antibodies were also used to clone a cDNA for the 37-kDa polypeptide. This cDNA contains an open reading frame predicted to produce a protein with several features, including two RNA recognition motifs and domains that potentially mediate protein-protein interactions. These results provide further support for a role of this protein in mediating ARE-directed mRNA degradation.
Zhang
W
W
Department of Microbiology and Immunology, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157-1064.
Wagner
B J
BJ
Ehrenman
K
K
Schaefer
A W
AW
DeMaria
C T
CT
Crater
D
D
DeHaven
K
K
Long
L
L
Brewer
G
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics*; D016259:Genes, myc; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D006801:Humans; D007120:Immunochemistry; D008969:Molecular Sequence Data; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification*; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism
D018076:DNA, Complementary; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D016601:RNA-Binding Proteins