Soluble retinoid carrier essential the proper function of both rod and cone photoreceptors. Participates in the regeneration of active 11-cis-retinol and 11-cis-retinaldehyde, from the inactive 11-trans products of the rhodopsin photocycle and in the de novo synthesis of these retinoids from 11-trans metabolic precursors. The cycling of retinoids between photoreceptor and adjacent pigment epithelium cells is known as the 'visual cycle'.
Retina and pineal gland. Not present in photoreceptor cells but is expressed abundantly in the adjacent retinal pigment epithelium (RPE) and in the Mueller glial cells of the retina.
Involvement in disease
Defects in RLBP1 are a cause of retinitis pigmentosa autosomal recessive (ARRP) [MIM:268000]. RP leads to degeneration of retinal photoreceptor cells. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well. Defects in RLBP1 are the cause of Bothnia retinal dystrophy (BRD) [MIM:607475]; also known as Vasterbotten dystrophy. Affected individuals show night blindness from early childhood with features consistent with retinitis punctata albescens and macular degeneration. Defects in RLBP1 are the cause of rod-cone dystrophy Newfoundland (NFRCD) [MIM:607476]. NFRCD is a retinal dystrophy reminiscent of retinitis punctata albescens but with a substantially lower age at onset and more-rapid and distinctive progression. Rod-cone dystrophies results from initial loss of rod photoreceptors, later followed by cone photoreceptors loss. Defects in RLBP1 are a cause of fundus albipunctatus (FA) [MIM:136880]. FA is a rare form of stationary night blindness characterized by a delay in the regeneration of cone and rod photopigments.