HPRT Locus Targeting

HPRT locus targeting successfully accommodates large genomic fragments, including BAC inserts spanning 100+ kilobases. Pre germline ES cell characterization confirms insertion structure regardless of insert size, ensuring researchers receive predictable models.

Heterozygous females carry one copy of the targeted HPRT allele and one wild-type allele on their second X chromosome. X inactivation results in approximately 50% of cells expressing the transgene, creating a mosaic tissue distribution. Hemizygous males express the transgene uniformly across all tissues.

HPRT locus expression generally yields intermediate levels suitable for most reporter and transgenic applications. Specific expression depends on the transgene promoter driving expression, the surrounding chromatin context, and the specific insert design. ES cell characterization does not predict transgene expression levels, so researchers should plan founder line screening.

Yes, HPRT safe harbor locus targeting is fully compatible with LoxP site insertion enabling Cre mediated excision. This combination creates conditional transgenic models where exogenous gene expression can be induced or eliminated in tissue specific or temporally controlled contexts.