Genomic structure of mouse IA-2: comparison with its human homologue.
OBJECTIVE
IA-2 is a transmembrane protein with a tyrosine phosphatase (PTP)-like structure and a major autoantigen in Type I (insulin-dependent) diabetes mellitus. Because the nucleotide sequence of human and mouse IA-2 cDNA are closely related, it seemed likely that the genomic organization of the two molecules would be similar. To test this possibility the current experiments were initiated to characterize and compare the genomic structure of mouse and human IA-2.


METHODS
IA-2 cDNA was used to screen a 129SVJ mouse genomic library. We selected and mapped 7 overlapping clones. The subcloned inserts were used to determine intron-exon junctions by direct sequencing. Polymerase chain reaction and restriction mapping were used to estimate the size of the introns.


RESULTS
The mouse IA-2 gene and the 5' upstream regulatory region were isolated and the intron-exon junctions determined. Mouse IA-2 encompasses approximately 20 kb and encodes 23 exons. Both the 3' and 5' ends were mapped by rapid amplification of cDNA ends (RACE) and a 2 kb 5'-upstream region was shown to have functional promoter activity.


CONCLUSIONS
Comparison of the genomic structure of mouse and human IA-2 shows that they have the same number of exons and nearly identical intron-exon junctions. The region around the major transcription start site of mouse IA-2 is similar to human IA-2 and other transmembrane protein tyrosine phosphatases. It is concluded that human and mouse IA-2 are highly conserved and derived from a common ancestral gene.
Saeki
K
K
Experimental Medicine Section, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, Maryland 20892-4322, USA.
Xie
J
J
Notkins
A L
AL
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D001483:Base Sequence; D017124:Conserved Sequence; D005091:Exons; D006801:Humans; D007438:Introns; D007515:Islets of Langerhans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics*; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
D001324:Autoantigens; D008565:Membrane Proteins; C516862:PTPRN protein, human; D017027:Protein Tyrosine Phosphatases; C516863:Ptprn protein, mouse; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8