Retroposition in a family of carcinoma-associated antigen genes.
The gene encoding the carcinoma-associated antigen defined by the monoclonal antibody GA733 is a member of a family of at least two type I membrane proteins. This study describes the mechanism of evolution of the GA733-1 and GA733-2 genes. A full-length cDNA clone for GA733-1 was obtained by screening a human placental library with a genomic DNA probe. Comparative analysis of the cDNA sequence with the previously determined genomic sequence confirmed that GA733-1 is an intronless gene. The GA733-2 gene encoding the monoclonal antibody-defined antigen was molecularly cloned with a cDNA probe and partially sequenced. Comparison of GA733-2 gene sequences with the previously established cDNA sequence revealed that this gene consists of nine exons. The putative promoter regions of the GA733-1 and GA733-2 genes are unrelated. These findings suggest that the GA733-1 gene was formed by the retroposition of the GA733-2 gene via an mRNA intermediate. Prior to retroposition, the GA733-2 gene had been affected by exon shuffling. Analysis of GA733-2 exons revealed that many delineate structural motifs. The GA733-1 retroposon was localized either to chromosome region 1p32-1p31 or to 1p13-1q12, and the GA733-2 founder gene was localized to chromosome 4q.
Linnenbach
A J
AJ
Wistar Institute, Philadelphia, Pennsylvania 19104.
Seng
B A
BA
Wu
S
S
Robbins
S
S
Scollon
M
M
Pyrc
J J
JJ
Druck
T
T
Huebner
K
K
D000595:Amino Acid Sequence; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1; D002894:Chromosomes, Human, Pair 4; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics*; D015894:Genome, Human; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D012333:RNA, Messenger / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D015295:Antigens, Tumor-Associated, Carbohydrate; D004251:DNA Transposable Elements; D012333:RNA, Messenger