Proteins Homologous to the Xenopus Germ Cell-Specific RNA-Binding Proteins p54/p56 Are Temporally Expressed in Mouse Male Germ Cells

Post–transcriptional control of gene expression during spermatogenesis

“…32 Y box proteins of 54 and 56 kDa originally were identified as components of stored maternal mRNPs in cytoplasmic extracts prepared from Xenopus laevis oocytes. 30,33 ᎐ 37 Homologues of the Xenopus p54rp56 proteins have been described in mouse testicular extracts and shown to have apparent molecular weights of 48r52 kDa 38 and the gene for the 52 kDa protein has been cloned and is referred to as mouse Y box protein, MSY1. 30 The mouse p48 and p52 Y box proteins are highly enriched in the testis and have been shown to bind non-specifically to various RNAs in vitro, including Prm-1, Prm-2, TP1, hGH and pGem-2 RNA.…”

“…30 The mouse p48 and p52 Y box proteins are highly enriched in the testis and have been shown to bind non-specifically to various RNAs in vitro, including Prm-1, Prm-2, TP1, hGH and pGem-2 RNA. 38 Although MSY1 fractionates with mRNPs in Nycodenz gradients, 30 it has not been demonstrated that p48 and p52 actually are associated with the protamine mRNAs in vivo.…”

Translation of a Testis-Specific Cu/Zn Superoxide Dismutase (SOD-1) mRNA Is Regulated by a 65-Kilodalton Protein Which Binds to Its 5′ Untranslated Region

“…In addition to the testicular RNA-binding proteins that interact with the 3Ј UTRs of mRNAs (18,40,41), p48 and p52, homologs of the Xenopus FRG Y2, p54 and p56 which function both as transcription factors and mRNA-masking proteins (48,49), are present in the testis (42). The testicular 48-and 52-kDa proteins not only bind to all RNA sequences including the 3Ј UTR of mP2 mRNA (42,64) but also bind to a conserved element in the promoter of testis-specific genes including protamine 2 (51).…”

“…The testicular 48-and 52-kDa proteins not only bind to all RNA sequences including the 3Ј UTR of mP2 mRNA (42,64) but also bind to a conserved element in the promoter of testis-specific genes including protamine 2 (51). Although sequence analysis of the two SOD-RBP peptides of 9 and 20 amino acids has not detected complete homology to any known protein in the GENEEMBL database, 6 consecutive amino acids that match a sequence in a transcription factor (16) suggest that SOD-RBP could be another RNA-binding protein from the testis that also binds to DNA.…”

“…The iron-responsive-element-binding protein, one of the best-characterized RNA-binding proteins, regulates cellular iron metabolism by binding to sequence elements in the 5Ј UTR of ferritin mRNA and the 3Ј UTR of transferrin receptor mRNA (30,31,34,38,67). Other RNA-binding proteins such as a cytoplasmic polyadenylation element-binding protein mediate mRNA poly(A) elongation during Xenopus oocyte maturation (25,52), a 70-kDa poly(A)-binding protein binds to poly(A) tails and helps stabilize mRNAs (9,60), and Xenopus p54 and p56 (47)(48)(49) or their mouse homologs p48 and p52 (42,64) function as masking proteins by binding to stored mRNAs in an apparent sequence-or structure-independent manner.…”