Binding of vitellogenin to specific receptors in oocyte membrane preparations of the ovoviviparous cockroach Nauphoeta cinerea

Abstract

An in vitro binding assay was developed to investigate the presence of specific binding sites for vitellogenin in oocyte membrane preparations of a cockroach. Vitellogenin binding reached equilibrium within 1 hr at both 4 and 26°C and was shown to be pH-dependent, specific, saturable and tissue specific. Analysis of saturation isotherms revealed a concentration of receptors of 120 fmol per oocyte near the middle of the first vitellogenic cycle. The amount of vitellogenin bound per oocyte increased progressively during oocyte maturation. Scatchard analysis revealed a K d of 5 × 10 −7 M, and determination of the rate constants for association and dissociation yielded a similar K d-value. Oocyte membrane preparations of Nauphoeta cinerea did not bind vitellogenin of the closely related cockroach, Leucophaea maderae, whereas oocyte membranes of the latter species did bind the vitellogenin of Nauphoeta cinerea.