The Oxygen-Regulated Protein (ORP) Family

An oxygen regulated protein, the parental member of this family, is of 2156 aas in length with possibly as many as 3 hydrophobic regions long enough to be  TMSs, one at residue 210, one at residue 1130 and one at residue 1250.  It is also called microtubule-associated protein, and it regulates the stability and length of the microtubule-based axoneme of photoreceptors. It is required for the differentiation of photoreceptor cells and plays a role in the organization of the outer segment of rod and cone photoreceptors ensuring the correct orientation and higher-order stacking of outer segment disks along the photoreceptor axoneme.