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The third component of complement: covalent attachment of a radioactive sugar to the labile binding site of C3 via the alternative pathway.

Publication ,  Journal Article
Mann, J; O'Brien, R; Hostetter, MK; Alper, CA; Rosen, FS; Babior, BM
Published in: J Immunol
June 1981

A complement- (C) fixing particle consisting of agarose beads to which 5-thioglucose was attached by a --S--S-- bond (agarose-thioglucose) was employed to investigate the mechanism of attachment of C3 to surfaces. When whole serum containing [125I] C3 was incubated with agarose-thioglucose, labeled C3b was taken up in a form that was not removed by 2 M NaCl but was released by 10 mM dithiothreitol. Deposition of DTT-releasable C3b was dependent upon the alternative pathway of C activation. Gel electrophoresis of DTT-releasable C3b from similar experiments performed with unlabeled serum and agarose-[3H]thioglucose showed that the liberated C3b contained a molecule of radioactive thioglucose attached to the alpha'-chain by a covalent bond that was stable to mercaptoethanol. We propose that the thioglucose-alpha' chain bond was formed during the course of C activation by a reaction between the "labile binding site" of newly released C3b and the (then) particle-bound sugar. This formulation implies that the reaction by which C3b attaches to 5-thioglucose in this system is the reaction responsible for opsonization by C3b, and that the C3b-linked sugar represents a marker for the labile binding site. Incubation of the particle-bound C3b in serum resulted in the cleavage of the covalently linked alpha'-chain to several smaller polypeptides, the major cleavage product having a m.w. of 70,000.

Duke Scholars

Published In

J Immunol

ISSN

0022-1767

Publication Date

June 1981

Volume

126

Issue

6

Start / End Page

2370 / 2372

Location

United States

Related Subject Headings

  • Sepharose
  • Magnesium
  • Immunology
  • Humans
  • Glucose
  • Egtazic Acid
  • Edetic Acid
  • Dithiothreitol
  • Complement Pathway, Alternative
  • Complement C3b
 

Citation

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Mann, J., O’Brien, R., Hostetter, M. K., Alper, C. A., Rosen, F. S., & Babior, B. M. (1981). The third component of complement: covalent attachment of a radioactive sugar to the labile binding site of C3 via the alternative pathway. J Immunol, 126(6), 2370–2372.
Mann, J., R. O’Brien, M. K. Hostetter, C. A. Alper, F. S. Rosen, and B. M. Babior. “The third component of complement: covalent attachment of a radioactive sugar to the labile binding site of C3 via the alternative pathway.J Immunol 126, no. 6 (June 1981): 2370–72.
Mann J, O’Brien R, Hostetter MK, Alper CA, Rosen FS, Babior BM. The third component of complement: covalent attachment of a radioactive sugar to the labile binding site of C3 via the alternative pathway. J Immunol. 1981 Jun;126(6):2370–2.
Mann J, O’Brien R, Hostetter MK, Alper CA, Rosen FS, Babior BM. The third component of complement: covalent attachment of a radioactive sugar to the labile binding site of C3 via the alternative pathway. J Immunol. 1981 Jun;126(6):2370–2372.

Published In

J Immunol

ISSN

0022-1767

Publication Date

June 1981

Volume

126

Issue

6

Start / End Page

2370 / 2372

Location

United States

Related Subject Headings

  • Sepharose
  • Magnesium
  • Immunology
  • Humans
  • Glucose
  • Egtazic Acid
  • Edetic Acid
  • Dithiothreitol
  • Complement Pathway, Alternative
  • Complement C3b