title: The brown protein of Drosophila melanogaster is similar to the white protein and to components of active transport complexes.
abstract: The brown gene of Drosophila melanogaster is required for deposition of pteridine pigments in the compound eye and other tissues. We isolated a ca. 150-kilobase region including brown by microdissection and chromosome walking using cosmids. Among the cDNAs identified by hybridization to the cosmids, one class hybridized to a genomic region that is interrupted in two brown mutants, bw and In(2LR)CK, and to 2.8- and 3.0-kilobase poly(A)+ RNAs which are altered in the mutants. Nucleotide sequencing of these cDNAs revealed that the two transcripts differ as a consequence of alternative poly(A) addition and that both encode the same predicted protein of 675 amino acids. Searches of available databases for amino acid sequence similarities detected a striking overall similarity of this predicted protein to that of the D. melanogaster white gene. The N-terminal portion aligned with the HisP family of membrane-associated ATP-binding proteins, most of which are subunits of active transport complexes in bacteria, and to two regions of the multidrug resistance P-glycoprotein. The C-terminal portion showed a structural similarity to integral membrane components of the same complexes. Taken together with earlier biochemical evidence that brown and white gene products are necessary for uptake of a pteridine precursor and genetic evidence that brown and white proteins interact, our results are consistent with suggestions that these proteins are subunits of a pteridine precursor permease.
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
authors.forename: T D
authors.initials: TD
authors.lastname: Dreesen
authors.forename: D H
authors.initials: DH
authors.lastname: Johnson
authors.forename: S
authors.initials: S
authors.lastname: Henikoff
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001693:Biological Transport, Active; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005136:Eye Proteins; D005796:Genes; D007301:Insect Hormones / Q000235:genetics*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011679:Pupa; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018528:ATP-Binding Cassette Transporters; D029721:Drosophila Proteins; D005136:Eye Proteins; D007301:Insect Hormones; C059253:bw protein, Drosophila; C059254:w protein, Drosophila; D004247:DNA