Sulfate contributes to the negative charge of podocalyxin, the major sialoglycoprotein of the glomerular filtration slits

Journal Article · Sat Jun 15 04:00:00 EDT 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.12.5398· OSTI ID:6100386

Dekan, G; Farquhar, M G ^[1]; Gabel, C ^[2]

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1. Univ. of California, San Diego, La Jolla (United States)
2. Pfizer Central Research, Groton, CT (United States)

Podocalyxin is the major sialoprotein of the rat glomerulus. Its function is to maintain the filtration slits of the glomerular epithelium open by virtue of its high net negative charge. The authors have used biosynthetic labeling and oligosaccharide analysis to characterize the anionic-charge-carrying moieties on this protein. Kidney slices from 2-day-old rats were biosynthetically labeled with ({sup 35}S)Cys, ({sup 3}H)Man, ({sup 3}H)GlcN, and {sup 35}SO{sub 4}, after which podocalyxin was immunoprecipitated and purified by SDS/PAGE. All these labels were incorporated into podocalyxin. Immunoprecipitates were subjected to digestion with specific glycosidases or digested with Pronase followed by chromatographic analysis of the released glycopeptides. Analysis of the {sup 35}SO{sub 4}-labeled glycopeptides indicated that both the N- and O-linked structures were sulfated. They conclude that in newborn rat kidney (i) podocalyxin contains both O- and N-linked oligosaccharides (ii) podocalyxin is sulfated, and (iii) sulfate is located on both O-linked oligosaccharides and on glycopeptides carrying tri- or tetrantennary N-linked structures. These results indicate that the net negative charge of podocalyxin is most likely derived from sulfate as well as from sialic acid residues.

• OSTI ID: 6100386
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 88:12; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL TISSUES
ANIMALS
ARTIFICIAL ORGANS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
BODY
CARBOHYDRATES
DAYS LIVING RADIOISOTOPES
ELECTROPHORESIS
EPITHELIUM
EVEN-ODD NUCLEI
GLOMERULI
GLYCOPROTEINS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MAMMALS
MECHANICAL KIDNEY
MEDICAL SUPPLIES
MONOSACCHARIDES
NUCLEI
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
PROSTHESES
PROTEINS
RADIOISOTOPES
RATS
RODENTS
SACCHARIDES
SIALIC ACID
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TISSUES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES