Electron microscopic demonstration of a common structural motif in human complement factor C3 and rat alpha 1-inhibitor 3 (murinoglobulin).
Electron microscopy of two homologous giant proteins revealed that complement factor C3 and alpha 1-inhibitor 3 have a common structural motif of a semicircularly bent string 18-20 nm long with two or three bumps indicating globular domains. C3 had a structure similar to the letter C with a small but distinct hole in the center. alpha 1-Inhibitor 3 was a more complete ring sometimes ajar at one corner. When the latter was treated with a proteinase, it became slightly flattened and adopted a squarish C-shape.
Ikai
A
A
Laboratory of Biodynamics, Tokyo Institute of Technology, Yokohama, Japan.
Nishigai
M
M
Saito
A
A
Sinohara
H
H
Muto
Y
Y
Arata
Y
Y
D000209:Acute-Phase Proteins; D000818:Animals; D003176:Complement C3 / Q000032:analysis* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D011480:Protease Inhibitors / Q000032:analysis*; D051381:Rats; D012712:Serum Globulins / Q000032:analysis* / Q000648:ultrastructure; D013194:Staining and Labeling; D013329:Structure-Activity Relationship
D000209:Acute-Phase Proteins; D003176:Complement C3; D011480:Protease Inhibitors; D012712:Serum Globulins; C017894:alpha 1-inhibitor 3; C044177:murinoglobulin