Isolation, characterization, and precise physical localization of human CDX1, a caudal-type homeobox gene.

The human CDX1 gene has been isolated from a small intestine cDNA library using a murine Cdx1 cDNA probe. The nucleotide sequence of CDX1 is 81% identical to murine Cdx1 and predicts a 265-amino-acid protein with 85% identity to the mouse protein (98% identity, including conservative amino acid changes). The CDX1 locus has been mapped to a cosmid contig from chromosome 5q31-q33, placing CDX1 approximately 100 kb distal to CSFIR. Expression of CDX1 in adults appears to be limited to the intestine and colon by Northern analysis, suggesting a possible role in the terminal differentiation of the intestine. Further analysis of CDX1 should elucidate the function of caudal-type homeobox genes in human development.