Photoreceptor rim protein: partial sequences of cDNA show a high degree of similarity to ABC transporters.
OBJECTIVE
To isolate and sequence cDNA for bovine rim protein, a large membrane-bound glycoprotein found in photoreceptor outer segments.


METHODS
Bovine rim protein was N-terminally sequenced (22 residues) and fragments were prepared by partial proteolysis. Two internal sequences of 21 and 18 amino acid residues were obtained from 35 kDa and 32 kDa fragments, respectively. Sense and anti-sense oligonucleotide primers were constructed, based on the peptide sequences derived from the 35 kDa and 32 kDa fragments, respectively, and the polymerase chain reaction (PCR) was used to amplify a 150 bp sequence from bovine retinal cDNA.


RESULTS
The amplified sequence coded for the remainder of the peptide sequence determined from the 35 kDa fragment, which was not present in the primer, confirming that it was derived from the rim protein. The 150 bp sequence was translated to give a 50 amino acid peptide. Part of this peptide was compared with Dna sequence databases using the TFastA program, which found 94.6% identity with an EST derived from human retina and 86.1% identity to the mouse abc1 transporter.


CONCLUSIONS
It is proposed that rim protein is a member of the ATP transporter family of proteins. It may be involved in transport of molecules involved in visual transduction across the photoreceptor disk membrane.
Thomson
J L
JL
Department of Pharmaceutical Sciences, University of Strathclyde, Glasgow, UK.
Brzeski
H
H
Dunbar
B
B
Forrester
J V
JV
Fothergill
J E
JE
Converse
C A
CA
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D018076:DNA, Complementary / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000378:metabolism*; D017385:Sequence Homology
D018528:ATP-Binding Cassette Transporters; C512841:Abca4 protein, mouse; D018076:DNA, Complementary; D008562:Membrane Glycoproteins