Ninety-five- and 25-kDa fragments of the human immunodeficiency virus envelope glycoprotein gp120 bind to the CD4 receptor
Iodine-125-labeled gp120 (120-kDa envelope glycoprotein) from the BH10 isolate of human immunodeficiency virus is cleaved to a limited extend with the glutamate-specific protease from Staphylococcus aureus. After disulfide bond reduction, fragments with approximate molecular masses of 95, 60, 50, and 25 kDa are produced. Tests for binding to CD4-positive cells show that only two fragments, the 95- and 25- kDa peptides, are observed in cleavage products that retain the selective binding capacity of gp120. Radiosequence analysis of the fragments after sodium dodecyl sulfate/polyacrylamide gel electrophoresis and electroblotting demonstrates that the 95-kDa fragment lacks the N-terminal region of gp120 and starts at position 143 of the mature envelope protein. The 50-kDa fragment starts at the same position. The 25-kDa binding fragment was similarly deduced to be generated as a small fragment from a cleavage site in the C-terminal part of gp120. The identifications of these fragments demonstrate that radiosequence analysis utilizing /sup 125/I-labeled tyrosine residues can function as a useful and reliable method for small-scale determination of cleavage sites in proteins. Combined, the data suggest domain-like subdivisions of gp120, define at least two intervening segments especially sensitive to proteolytic cleavage, and demonstrate the presence of a functional region for receptor binding in the C-terminal part of the molecule.
- Research Organization:
- Karolinska Institutet, Stockholm (Sweden)
- OSTI ID:
- 5821949
- Journal Information:
- Proc. Natl. Acad. Sci. USA; (United States), Vol. 85:17
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AIDS VIRUS
BIOCHEMISTRY
GLUCOPROTEINS
AMINO ACID SEQUENCE
CROSS-LINKING
RECEPTORS
ELECTROPHORESIS
IODINE 125
LABELLED COMPOUNDS
TYROSINE
AMINO ACIDS
BETA DECAY RADIOISOTOPES
CARBOHYDRATES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
GLYCOPROTEINS
HYDROXY ACIDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
MEMBRANE PROTEINS
MICROORGANISMS
MOLECULAR STRUCTURE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PARASITES
POLYMERIZATION
PROTEINS
RADIOISOTOPES
SACCHARIDES
VIRUSES
550201* - Biochemistry- Tracer Techniques