Retinal outer segment membrane protein 1 (ROM1)

Retinal outer segment membrane protein 1 (ROM1) is a photoreceptor-specific tetraspanin family member that serves as an integral membrane protein located in the photoreceptor disc rim of the eye[1][3]. ROM1 functions as a molecular building block for the formation of light-sensitive disc membranes in photoreceptor outer segments, working in conjunction with peripherin-2 (PRPH2)[1][2]. The protein plays a crucial role in disc morphogenesis and can form both homodimers and heterodimers with PRPH2[1][2][3]. ROM1 and PRPH2 exist as a core heterotetrameric complex with an estimated molecular weight of approximately 150 kDa[2]. This complex exhibits a 2-fold symmetry and has the ability to induce membrane curvature when reconstituted in lipid vesicles[2]. ROM1 contributes to several critical aspects of photoreceptor function, including the formation of disc rims, the process of disc enclosure, and the maintenance of disc structure[1]. Notably, ROM1 is involved in the formation of incisures - deep indentations found in normal mouse disc rims[1]. The protein also functions as an adhesion molecule involved in the stabilization and compaction of outer segment discs and may help maintain the curvature of the disc rim[3]. While ROM1 is important for normal photoreceptor function, research has demonstrated functional redundancy between ROM1 and PRPH2. In ROM1 knockout mice, there is a compensatory increase in PRPH2 content, and the morphological defects can be rescued by transgenic overexpression of PRPH2[1]. This suggests that while ROM1 contributes unique features to tetraspanin oligomer properties, it can be functionally replaced by sufficient amounts of PRPH2[1]. ROM1 deficiency leads to several structural abnormalities in photoreceptor outer segments, including delayed disc maturation, increased outer segment diameter, loss of disc incisures, and occasional formation of membranous whorls[1]. These structural defects eventually lead to photoreceptor degeneration[1]. Mutations in ROM1 have been associated with retinitis pigmentosa and other degenerative eye diseases, though ROM1 mutations alone causing human visual pathology appear to be limited compared to PRPH2 mutations[1][3]. The protein belongs to the tetraspanin family (TSPAN23) and is essential for proper disc morphogenesis in the photoreceptor outer segments, making it a critical component for vision function[1][2][3].

Other names

TSPAN23ROMROSP1Tetraspanin-23Rod outer segment membrane protein 1Tspan-23RP7retinal outer segment membrane protein 1tetraspanin-23