Fig. 1. Domain architecture of the midgut chitin synthase CHS2. The two black horizontal lines represent the apical brush border membrane of midgut columnar cells. Horizontal bars represent intra- or extracellular domains and vertical bars transmembrane helices. (A) Aminoterminal transmembrane region; (B) cytoplasmic catalytic domain; (C) carboxyterminal transmembrane region; the numbers refer to single domains within each region. Those domains that were tested as baits in the yeast two-hybrid system are coloured dark grey. UDP, uridine 5'-diphosphate; GlcNAc, N-acetyl-D-glucosamine.