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GLYCOPROTEINS AND GLYCOLIPIDS OF SUBCELLULAR FRACTIONS FROM BOVINE RETINA. INCORPORATION OF MANNOSE AND SIALIC ACID 1
Author(s) -
Curtino J. A.,
Maccioni H. J.,
Caputto R.
Publication year - 1977
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1977.tb10631.x
Subject(s) - mannose , glycolipid , biochemistry , membrane , gel electrophoresis , chemistry , sialic acid , chromatography , biology
— Endogenous lipids and proteins of bovine retina subcellular fractions were labelled from CMP‐[ 3 H]NeuNAc and GDP‐[ 14 C]mannose. The bulk of NeuNAc and mannose transfer activity was in membranes other than those from the rod outer segment (ROS). Lighter and heavier membranes, obtained from ROS free membranes by density gradient centrifugation, were the most active for the incorporation of NeuNAc and mannose, respectively. NeuNAc bound to a lipid indistinguishable from gangliosides, and a lipid that contains mannose (mannolipid‐I) were found in the fraction extractable with chloroform‐methanol (2:1, v/v). Mannose was also incorporated into a lipid fraction extractable with chloroform‐methanol‐water (1:1:0.3, by vol) (mannolipid‐II). Mannolipid‐I and mannolipid‐II were labile to mild acid hydrolysis. In the presence of ROS free membranes, radioactivity of mannoli‐pid‐I was transferred to mannolipid‐II and from this to proteins. Analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis, the proteins labelled from GDP‐mannose migrated as a broad peak covering the range of molecular weights 20,000–30,000 and including the zone of rhodopsin migration. The proteins labelled from CMP‐NeuNAc showed four radioactive peaks that were coincident with three out of four periodic acid‐Schiff (PAS) positive bands.