Characterization of genes encoding translation initiation factor eIF-2gamma in mouse and human: sex chromosome localization, escape from X-inactivation and evolution.
The Delta Sxrb interval of the mouse Y chromosome is critical for spermatogenesis and expression of the male-specific minor transplantation antigen H-Y. Several genes have been mapped to this interval and each has a homologue on the X chromosome. Four, Zfy1 , Zfy2 , Ube1y and Dffry , are expressed specifically in the testis and their X homologues are not transcribed from the inactive X chromosome. A further two, Smcy and Uty , are ubiquitously expressed and their X homologues escape X-inactivation. Here we report the identification of another gene from this region of the mouse Y chromosome. It encodes the highly conserved eukaryotic translation initiation factor eIF-2gamma. In the mouse this gene is ubiquitously expressed, has an X chromosome homologue which maps close to Dmd and escapes X-inactivation. The coding regions of the X and Y genes show 86% nucleotide identity and encode putative products with 98% amino acid identity. In humans, the eIF-2gamma structural gene is located on the X chromosome at Xp21 and this also escapes X-inactivation. However, there is no evidence of a Y copy of this gene in humans. We have identified autosomal retroposons of eIF-2gamma in both humans and mice and an additional retroposon on the X chromosome in some mouse strains. Ark blot analysis of eutherian and metatherian genomic DNA indicates that X-Y homologues are present in all species tested except simian primates and kangaroo and that retroposons are common to a wide range of mammals. These results shed light on the evolution of X-Y homologous genes.
Ehrmann
I E
IE
Transplantation Biology Group, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK.
Ellis
P S
PS
Mazeyrat
S
S
Duthie
S
S
Brockdorff
N
N
Mattei
M G
MG
Gavin
M A
MA
Affara
N A
NA
Brown
G M
GM
Simpson
E
E
Mitchell
M J
MJ
Scott
D M
DM
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002874:Chromosome Mapping; D002877:Chromosomes, Human; D002881:Chromosomes, Human, Pair 12; D003001:Cloning, Molecular; D004303:Dosage Compensation, Genetic; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D006801:Humans; D008297:Male; D008322:Mammals / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D018626:Retroelements; D017386:Sequence Homology, Amino Acid; D012730:Sex Chromosomes; D014960:X Chromosome; D014998:Y Chromosome
D015852:Eukaryotic Initiation Factor-2; D018626:Retroelements