The mouse Id2 and Id4 genes: structural organization and chromosomal localization.

The Id proteins belong to a family of nuclear HLH proteins lacking a basic region and thought to function as dominant-negative regulators of bHLH proteins during cell growth and differentiation. In this paper, we report the genomic organization of the mouse Id2 and Id4 genes. These genes each span approximately 3 kb of the mouse genome and are each organized as three exons with recognizable splice donor and acceptor consensus sequences. Their genomic organization is very similar, consistent with their having evolved from a common, ancestral Id-like gene. Using FISH analysis, we have localized the mouse Id2 and Id4 genes to mouse chromosome 12 and 13, respectively.