a highly conserved extracellular protein essential for proper retinal structure. Must interact with L-type voltage-gated calcium channels (L-VGCCs) correctly so that the photoreceptor cells in the eye can function properly. Genetic mutations in RS1 cause X-linked retinoschisis (XLRS) and early onset of macular degeneration. Interacts with the L-VGCCa1D subunit, regulating its activity. The expression and secretion of retinoschisin are modulated by circadian rhythms, peaking at night and diminishing during the day. Note: This description may include information from UniProtKB.