Id1^tm1Bene

The coding sequence of the Venus yellow fluorescent protein was linked to the 3' end of the Id1 coding sequence with a sequence for a 10-amino acid flexible linker (GSAGSAAGSG) to create an Id1/YFP fusion protein. Following this insertion, the endogenous 3' untranslated region was unperturbed and utilized as the polyadenylation sequence. The FRT-Neo-FRT cassette for positive selection was inserted 477 bp downstream of the modified Id1 gene. CY2.4 ES cells (albino C57BL/6 derivation) were used for targeting. Southern blot positive ESC clones were injected into co-isogenic B6J blastocysts. Positive chimeras were bred to albino B6J females. Albino pups were genotyped by PCR, and positive pups were bred to B6 ACTB::FLPE mice (Artemis Pharamaceuticals) to excise the Neo cassette in vivo. (J:154023)