ChemBioChem

Cover Picture: The Molecular Mechanism of the Termination of Insect Diapause, Part 1: A Timer Protein, TIME-EA4, in the Diapause Eggs of the Silkworm Bombyx mori is a Metallo-Glycoprotein (ChemBioChem 10/2006)

The cover picture shows a timer protein for measuring the time interval of the termination of insect diapause. It is a computer generated 3D structure of the time-interval-measuring enzyme–esterase A4 (TIME-EA4), a Cu₂,Zn-SOD-type metalloglycoprotein found in diapause eggs of the Bombyx silkworm. The particles in the rings are mixtures of colored diapause and nondiapause eggs. The latter keep growing until the black worms hatch. The diapause eggs, on the other hand, must go through a cold period (represented by the blue arrow), as in winter, before they can eventually hatch. TIME-EA4 starts measuring the time intervals during the cold period. The article by M. Isobe et al. on p. 1590 ff describes the structure and the possible molecular mechanisms of this timer protein.

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