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Characterization of a truncated form of arrestin isolated from bovine rod outer segments
Author(s) -
Palczewski Krzysztof,
Buczylko Janina,
Ohguro Hiroshi,
Annan Roland S.,
Carr Steven A.,
Crabb John W.,
Kaplan Michael W.,
Johnson Richard S.,
Walsh Kenneth A.
Publication year - 1994
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560030215
Subject(s) - characterization (materials science) , chemistry , biophysics , crystallography , biology , materials science , nanotechnology
The inactivation of photolyzed rhodopsin requires phosphorylation of the receptor and binding of a 48‐kDa regulatory protein, arrestin. By binding to phosphorylated photolyzed rhodopsin, arrestin inhibits G protein (G t ) activation and blocks premature dephosphorylation, thereby preventing the reentry of photolyzed rhodopsin into the phototransduction pathway. In this study, we isolated a 44‐kDa form of arrestin, called p 44 , from fresh bovine rod outer segments and characterized its structure and function. A partial primary structure of p 44 was established by a combination of mass spectrometry and automated Edman degradation of proteolytic peptides. The amino acid sequence was found to be identical with arrestin, except that the C‐terminal 35 residues (positions 370‐404) are replaced by a single alanine. p 44 appeared to be generated by alternative mRNA splicing, because intron 15 interrupts within the nucleotide codon for 369 Ser in the arrestin gene. Functionally, p 44 binds avidly to photolyzed or phosphorylated and photolyzed rhodopsin. As a consequence of its relatively high affinity for bleached rhodopsin, p 44 blocks G t activation. The binding characteristics of p 44 set it apart from tryptic forms of arrestin (truncated at the N‐ and C‐termini), which require phosphorylation of rhodopsin for tight binding. We propose that p 44 is a novel splice variant of arrestin that could be involved in the regulation of G t activation.