Binding of active components of compound 48/80 to rat peritoneal mast cells.
The binding characteristics of compound 48/80 were examined using rat mast cells and fractionated 14C-labeled compound 48/80 components at 4 degrees C in vitro where no degranulation of the cells occurred. The binding potencies of these components in the presence of Ca2+ generally paralleled their histamine releasing activities, except in the case of fractions G (decamer) and H (nonamer), both Ca2+-independent releasers, for the binding of which Ca2+ was inhibitory. Scatchard analyses and displacement studies indicated that the mast cells had two types of binding sites with high and low affinities for fractions D (tridecamer, Ca2+-dependent releaser, Kd = 3.41 X 10(-8) M and 3.35 X 10(-6) M) and H (Ca2+-independent releaser, Kd = 1.11 X 10(-7) M and 9.11 X 10(-6) M), respectively. These sites partially overlapped each other, and also the fraction D site partially overlapped the IgE site and the fraction H site overlapped the neurotensin or substance P site.
Y
Y
Koibuchi
A
A
Ichikawa
M
M
Nakagawa
K
K
Tomita
D000818:Animals; D000947:Antigens, Helminth / Q000008:administration & dosage; D001200:Ascaris / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D007114:Immunization; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D009496:Neurotensin / Q000494:pharmacology; D010537:Peritoneum / Q000378:metabolism; D051381:Rats; D013373:Substance P / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D003189:p-Methoxy-N-methylphenethylamine / Q000378:metabolism*
D000947:Antigens, Helminth; D013373:Substance P; D009496:Neurotensin; D003189:p-Methoxy-N-methylphenethylamine; D002118:Calcium