Mmp20^tm1Jdb

Sequence encompassing a portion of intron 4 and all of exon 5 was replaced with a Hprt minigene inserted by homologous recombination. The deleted region encoded the conserved zinc-binding site of the catalytic domain. Northern blot analysis of total RNA obtained from homozygous mutant incisor homogenates indicated a lack of transcript containing exon 5. Enamelysin activity was undetected by zymography of proteins isolated from molars of postnatal homozygous mutant mice. (J:80925)