Molecular cloning of Drosophila Rh6 rhodopsin: the visual pigment of a subset of R8 photoreceptor cells.
By screening retinal cDNA libraries for photoreceptor-specifically expressed genes we have isolated and sequenced a cDNA clone encoding the rhodopsin (Rh6) of a subset of R8 photoreceptor cells of the Drosophila compound eye. Compared to the other visual pigments of Drosophila, this rhodopsin is equally homologous to Rh1 and Rh2 (51% amino acid identity) but shows only 32% and 33% amino acid identity with Rh3 and Rh4, respectively. The open reading frame codes for a protein of 369 amino acids (MW = 41691). The primary structure of Rh6 displays sites typical for rhodopsin molecules in general, for example, a chromophore binding site in transmembrane domain VII, sequence motifs in the intracellular loops 2 and 3 required for the binding of a heterotrimeric G-protein, and a glycosylation site near the N-terminus which seems to be important for protein transport and maturation. Since R8 cells are founder cells in the developing compound eye, the isolation of a rhodopsin gene expressed in these cells may aid the understanding of terminal differentiation of photoreceptor cells.
Huber
A
A
Universität Karlsruhe, Institut für Zoologie I, Germany. DC05@rz.uni-karlsruhe.de
Schulz
S
S
Bentrop
J
J
Groell
C
C
Wolfrum
U
U
Paulsen
R
R
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D008969:Molecular Sequence Data; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism*; D010860:Pigments, Biological / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012243:Rhodopsin / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D029721:Drosophila Proteins; D010860:Pigments, Biological; D012333:RNA, Messenger; C105578:Rh6 protein, Drosophila; D012243:Rhodopsin