PHR1, a PH domain-containing protein expressed in primary sensory neurons.

Previously, we identified PHR1 as an abundantly expressed gene in photoreceptors and showed that it encodes four isoforms, each with N-terminal pleckstrin homology (PH) and C-terminal transmembrane domains. To better understand PHR1 function and expression, we made a Phr1 null mouse by inserting a beta-galactosidase/neo(r) cassette into exon 3. In addition to photoreceptors, we found abundant expression of specific Phr1 splice forms in olfactory receptor neurons and vestibular and cochlear hair cells. We also found Phr1 expression in cells with a possible sensory function, including peripheral retinal ganglion cells, cochlear interdental cells, and neurons of the circumventricular organ. Despite this discrete expression in known and putative sensory neurons, mice lacking PHR1 do not have overt sensory deficits.