Role of C8 binding protein in homologous species restriction of C-mediated lysis: the C8bp interacts with. cap alpha. -. gamma. subunit of C8, and inhibits C9 polymerization
The lysis of human (hu) erythrocytes (E) by C5b-9 is inefficient when hu C8/C9 are used to lyse EC5b-7. In the classical pathway activation, the ratio of C9 bound/inserted in hu E lysed with hu C is much lower when compared to sheep E. Recently, the authors have identified a protein from hu E that binds to hu C8. This C8 binding protein (C8bp) isolated from E inhibited lysis of chicken EC5b-7 by hu C8/C9, but not rabbit C8/C9. When hu C8/C9 were added to hu EC5b-7 with C8bp, poly C9 formation was inhibited. In the present study, the interaction of C8bp with C8 was further explored with /sup 125/I-labeled C8bp. Hu C8 was separated by SDS-PAGE under reducing or non-reducing conditions, transferred onto nitrocellulose paper by Western-blot. The blots were reacted with /sup 125/I-C8bp. Autoradiographic analysis showed the C8bp bands corresponding to the ..cap alpha..-..gamma.. subunit in a non-reduced gel and the ..gamma..-chain in a reduced gel, indicating direct interaction between C8bp and ..gamma..-chain of C8. Since the ..cap alpha gamma..-subunit does not bind to C5b-7, the authors' observation also explains the failure of C8bp to inhibit C8 binding to EC5b-7 shown previously. Inhibition of C5b-8 induced C9 polymerization by C8bp also suggests a direct effect of C8bp on C9 interaction with EC5b-8.
- Research Organization:
- Univ. of Heidelberg, West Germany
- OSTI ID:
- 5385484
- Report Number(s):
- CONF-8604222-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:3; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BIOLOGICAL PATHWAYS
BIRDS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHICKENS
COMPLEMENT
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
ERYTHROCYTES
FOWL
INHIBITION
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
LYSIS
MAMMALS
MAN
MATERIALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
RABBITS
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
SHEEP
VERTEBRATES