| Modification Notes |
Pleckstrin homology domain retinal protein 1 (PHR1), also designated pleckstrin homology domain-containing family B member 1, is a membrane protein that contains a pleckstrin homology (PH) domain at its N-terminus and a 27 amino acid transmembrane segment at its C-terminus, along with several casein kinase II phosphorylation sites and a putative protein kinase C (PKC) phosphorylation site. The full-length mouse and human PHR1 proteins contain 243 amino acid residues and share 94% sequence identity. The presence of two transcription start sites and alternative splicing results in four PHR1 isoforms in both humans and mice. All PHR1 isoforms bind to transducin ∫© subunits, the binding of which is dependent upon the N-terminal 137 residues of full-length PHR1. This suggests that the PH domain (amino acids 21 to 128), which is present in all PHR1 isoforms, mediates binding. PHR1 shows predominant expression in the outer segments of photoreceptor cells, both in rods and cones, as well as in retina and brain tissues. |