Characterization of N-acylation of Go alpha purified from bovine retinas

HETEROGENEOUS N-terminal acylation has been identified in several retinal p roteins localized predominantly in the outer segments of the photoreceptor cells, but it is still unclear whether such a unique heteroacylation is det ermined by a photoreceptor cell-specific factor or not. Here, we characteri zed the N-terminal modification of bovine retinal Go alpha, which seems to be involved in the: neural activities and is not detected in the photorecep tor outer segments. In the proteolytic fragments of immunoaffinity-purified retinal Go alpha, we found a: single N-terminal peptide modified with myri state, and concluded that retinal Go alpha is purely myristoylated, just li ke brain Goa alpha. This result indicates that the heteroacylation has a mo re restricted origin in the retina,and supports the idea that it is a photo receptor cell-specific modification. (C) 1999 Lippincott Williams & Wilkins .