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Binding of juvenile hormone III to lipophorin from the american cockroach Periplaneta americana
Author(s) -
De Kort Stan,
Koopmanschap Bertha
Publication year - 1989
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.940110304
Subject(s) - periplaneta , hemolymph , american cockroach , cockroach , biology , juvenile hormone , dissociation constant , biochemistry , polyacrylamide gel electrophoresis , enzyme , hormone , receptor , ecology
Whole hemolymph from the American cockroach, Periplaneta americana , efficiently binds juvenile hormone (JH) III and to a lesser extent JH‐I and 10, 11‐epoxyfarnesyl diazoacetate (EFDA). The dissociation constants for racemic JH‐III and EFDA are 30 ± 2 nM and 1.0 μM, respectively. Isolated lipophorin also binds [ 3 H]JH‐III and to a lesser extent JH‐I. Other proteins from the hemolymph do not bind JH‐III. Binding of JH‐III to lipophorin is enantioselective. The dissociation constant, measured with a 92% 10R and 8% 10S mixture, is 21 ± 2 nM. Each lipophorin molecule contains one specific binding site for JH‐III. It is concluded that lipophorin is the JH‐III‐specific transport protein in the hemolymph of the American cockroach. By a combination of photoaffinity labelling and gradient electrophoresis with sodium dodecyl sulphate on polyacrylamide gel, we showed that the JH‐III‐specific binding site is probably located on apolipophorin I.