Phosducin is an abundant photoreceptor-specific protein. Mice homozygous for the phosducin knockout allele (Pd-/- or Pdc-/-) are viable and fertile with normal lifespan and no gross abnormalities. See breeding performance below.
Phosducin protein is completely absent in Pd-/- retinas. The rods and cones of Pd-/- mice have reduced levels of the photoreceptor-specific G protein transducin (20-30% and 40% reduction, respectively), and also exhibit impaired light-dependent transducin translocation. In addition, both rod- and cone-driven pathways behave as if persistently desensitized/illuminated, with cone-driven pathways affected most significantly. Specifically, homozygous mice have reduced bipolar cell response sensitivity in the dark and a lesser degree of response desensitization compared to wildtype.
The donating investigator reports the breeding performance of homozygous matings as averaging four pups per litter. Therefore, they suggest homozygous males be placed into breeding pairs at six weeks of age (and they have successful breeding for at least eight months); the age when homozygous females are bred is not as critical.
While other published phosducin knockout mice are reported to have stress-mediated hypertension (despite normal cardiac function and vascular reactivity) and elevated catecholamine turnover in the peripheral sympathetic system, such phenotypes have not been characterized for these Pd-/- mice (Stock No. 025987) to date (September 2014).
