Rhodopsin: The Functional Significance of Asn-Linked Glycosylation and Other Post-Translational Modifications

Abstract

Rhodopsin, the G-protein coupled receptor in retinal rod photoreceptors, is a highly conserved protein that undergoes several types of post-translational modifications. These modifications are essential to maintain the protein's structure as well as its proper function in the visual transduction cycle. Rhodopsin is N-glycosylated at Asn-2 and Asn-15 in its extracellular N-terminal domain. Mutations within the glycosylation consensus sequences of rhodopsin cause autosomal dominant retinitis pigmentosa, a disease that leads to blindness. Several groups have studied the role of rhodopsin's N-linked glycan chains in protein structure and function using a variety of approaches. These include the generation of a transgenic mouse model, study of a naturally occurring mutant animal model, in vivo pharmacological inhibition of glycosylation, and in vitro analyses using transfected COS-1 cells. These studies have provided insights into the possible role of rhodopsin glycosylation, but have yielded conflicting results.

Keywords:

• Rhodopsin
• glycosylation
• retina
• post-translational modifications
• retinal diseases

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Erratum