Identification and characterization of human Mex-3 proteins, a novel family of evolutionarily conserved RNA-binding proteins differentially localized to processing bodies.
In Caenorhabditis elegans, the Mex-3 protein is a translational regulator that specifies the posterior blastomere identity in the early embryo and contributes to the maintenance of the germline totipotency. We have now identified a family of four homologous human Mex-3 genes, called hMex-3A to -3D that encode proteins containing two heterogeneous nuclear ribonucleoprotein K homology (KH) domains and one carboxy-terminal RING finger module. The hMex-3 are phosphoproteins that bind RNA through their KH domains and shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway. Our analysis further revealed that hMex-3A and hMex-3B, but not hMex-3C, colocalize with both the hDcp1a decapping factor and Argonaute (Ago) proteins in processing bodies (P bodies), recently characterized as centers of mRNA turnover. Taken together, these findings indicate that hMex-3 proteins constitute a novel family of evolutionarily conserved RNA-binding proteins, differentially recruited to P bodies and potentially involved in post-transcriptional regulatory mechanisms.
Buchet-Poyau
Karine
K
Université de Lyon, Lyon, F-69003, France.
Courchet
Julien
J
Le Hir
Hervé
H
Séraphin
Bertrand
B
Scoazec
Jean-Yves
JY
Duret
Laurent
L
Domon-Dell
Claire
C
Freund
Jean-Noël
JN
Billaud
Marc
M
D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017124:Conserved Sequence; D022083:Cytoplasmic Structures / Q000737:chemistry / Q000378:metabolism; D019143:Evolution, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D010750:Phosphoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000032:analysis* / Q000235:genetics* / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D029742:Caenorhabditis elegans Proteins; C102175:MEX-3 protein, C elegans; C519162:MEX3A protein, human; C519163:MEX3B protein, human; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D034743:RNA-Induced Silencing Complex