Altered expression of a novel adaptin leads to defective pigment granule biogenesis in the Drosophila eye color mutant garnet.
Drosophila eye pigmentation defects have thus far been attributed to mutations in genes encoding enzymes required for biosynthesis of pigments and to ABC-type membrane transporters for pigments or their precursors. We report here that a defect in a gene encoding a putative coat adaptor protein leads to the eye color defect of garnet mutants. We first identified a human cDNA encoding delta-adaptin, a structural homolog of the alpha- and gamma-adaptin subunits of the clathrin coat adaptors AP-1 and AP-2, respectively. Biochemical analyses demonstrated that delta-adaptin is a component of the adaptor-like complex AP-3 in human cells. We then isolated a full-length cDNA encoding the Drosophila ortholog of delta-adaptin and found that transcripts specified by this cDNA are altered in garnet mutant flies. Examination by light and electron microscopy indicated that these mutant flies have reduced numbers of eye pigment granules, which correlates with decreased levels of both pteridine (red) and ommachrome (brown) pigments. Thus, the eye pigmentation defect in the Drosophila garnet mutant may be attributed to compromised function of a coat protein involved in intracellular transport processes required for biogenesis or function of pigment granules.
Ooi
C E
CE
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Moreira
J E
JE
Dell'Angelica
E C
EC
Poy
G
G
Wassarman
D A
DA
Bonifacino
J S
JS
D033965:Adaptor Protein Complex alpha Subunits; D033981:Adaptor Protein Complex delta Subunits; D033982:Adaptor Protein Complex gamma Subunits; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active; D018076:DNA, Complementary / Q000235:genetics; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism* / Q000648:ultrastructure; D005123:Eye / Q000648:ultrastructure; D005127:Eye Color / Q000235:genetics* / Q000502:physiology*; D015870:Gene Expression; D017344:Genes, Insect; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D034041:Monomeric Clathrin Assembly Proteins; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012168:Retinal Pigments / Q000096:biosynthesis* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D033965:Adaptor Protein Complex alpha Subunits; D033981:Adaptor Protein Complex delta Subunits; D033982:Adaptor Protein Complex gamma Subunits; D033942:Adaptor Proteins, Vesicular Transport; D018076:DNA, Complementary; D008565:Membrane Proteins; D034041:Monomeric Clathrin Assembly Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012168:Retinal Pigments; C439023:clathrin assembly protein AP180