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2.
J Mol Evol ; 41(5): 646-56, 1995 Nov.
Article in English | MEDLINE | ID: mdl-7490779

ABSTRACT

Vitamin A and fatty acids are critical to photoreceptor structure, function, and development. The transport of these nutrients between the pigment epithelium and neural retina is mediated by interphotoreceptor retinoid-binding protein (IRBP). IRBP, a 133-kDa (human) glycolipoprotein, is the major protein component of the extracellular matrix separating these two cell layers. In amphibians and mammals, IRBP consists of four homologous repeats of about 300 amino acids which form two retinol and four fatty acid-binding sites. Here we show that IRBP in teleosts is a simpler protein composed of only two repeats. Western blot analysis shows that goldfish IRBP is half the size (70 kDa) of IRBP in higher vertebrates. Metabolic labeling studies employing Brefeldin A taken together with in situ hybridization studies and the presence of a signal peptide show that goldfish IRBP is secreted by the cone photoreceptors. The translated amino acid sequence has a calculated molecular weight of 66.7 kDa. The primary structure consists of only two homologous repeats with a similarity score of 52.5%. The last repeats of human and goldfish IRBPs are 69.1% similar with hydrophobic regions being the most similar. These data suggest that two repeats were lost during the evolution of the ray-finned fish (Actinopterygii), or that the IRBP gene duplicated between the emergence of bony fish (Osteichthyes) and amphibians. Acquisition of a multirepeat structure may reflect evolutionary pressure to efficiently transport higher levels of hydrophobic molecules within a finite space. Quadruplication of an ancestral IRBP gene may have been an important event in the evolution of photo-receptors in higher vertebrates.


Subject(s)
Eye Proteins/metabolism , Goldfish/physiology , Repetitive Sequences, Nucleic Acid , Retinal Cone Photoreceptor Cells/metabolism , Retinol-Binding Proteins/metabolism , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Blotting, Western , DNA, Complementary/genetics , Dark Adaptation , Eye Proteins/genetics , Gene Library , Goldfish/genetics , In Situ Hybridization , Molecular Sequence Data , Organ Culture Techniques , Retinal Cone Photoreceptor Cells/cytology , Retinol-Binding Proteins/genetics , Sequence Analysis, DNA , Sequence Homology, Amino Acid
3.
J Neuroophthalmol ; 15(2): 98-101, 1995 Jun.
Article in English | MEDLINE | ID: mdl-7550937

ABSTRACT

Progressive, painful ophthalmoplegia developed in a 34-year-old man. MRI scan revealed an enhancing mass in the left cavernous sinus. Histologic examination of resected tumor revealed reticulin staining and cytologic features of hemangiopericytoma. Characteristics of intracranial hemangiopericytoma are reviewed.


Subject(s)
Brain Neoplasms/complications , Cavernous Sinus , Hemangiopericytoma/complications , Ophthalmoplegia/etiology , Pain/etiology , Adult , Brain Neoplasms/pathology , Brain Neoplasms/surgery , Gadolinium , Hemangiopericytoma/pathology , Hemangiopericytoma/surgery , Humans , Magnetic Resonance Imaging , Male
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