The protein in the properdin pathway responsible for conversion of precursor factor D to D has been isolated and found to be identical with properdin. Sequential ion exchange and gel filtration chromatography demonstrated identity between properdin protein, measured by radial immunodiffusion, and the capacity to activate D to D, assessed by formation of the intermediate, EAC43B(D). Properdin, purified in this manner, was homogeneous on acid polyacrylamide disc gel electrophoretic analysis, with the band of protein corresponding to the position of eluates in the replicate gel capable of activating highly purified D. Demonstration of the homogeneity of purified D by alkaline disc gel electrophoresis, coupled with the linear stoichiometric hemolytic titrations of each factor, indicates that direct interaction between properdin and D generates D. Thus, activation of D by properdin represents a mechanism in the properdin pathway by which D becomes available for formation of the C3b-dependent C3 convertase.
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August 01 1974
PROPERDIN FACTOR D : II. ACTIVATION TO D BY PROPERDIN
Douglas T. Fearon,
Douglas T. Fearon
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
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K. Frank Austen,
K. Frank Austen
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
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Shaun Ruddy
Shaun Ruddy
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
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Douglas T. Fearon
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
K. Frank Austen
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
Shaun Ruddy
From the Departments of Medicine, Harvard Medical School and the Robert B. Brigham Hospital, Boston, Massachusetts 02120
Received:
March 11 1974
Online ISSN: 1540-9538
Print ISSN: 0022-1007
Copyright © 1974 by The Rockefeller University Press
1974
J Exp Med (1974) 140 (2): 426–436.
Article history
Received:
March 11 1974
Citation
Douglas T. Fearon, K. Frank Austen, Shaun Ruddy; PROPERDIN FACTOR D : II. ACTIVATION TO D BY PROPERDIN . J Exp Med 1 August 1974; 140 (2): 426–436. doi: https://doi.org/10.1084/jem.140.2.426
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