cDNA-inferred amino-acid sequence of a C protein, a heparin-binding, basic secretion product of the tubular accessory sex glands of the mealworm beetle, Tenebrio molitor.

C proteins represent one of the four major protein groups secreted by the tubular accessory glands of male mealworm beetles (Tenebrio molitor). They are basic proteins with an apparent molecular mass of 21.9 kDa. In this paper we present the deduced amino-acid sequence of two, almost identical C proteins, termed C1 and C2. The C proteins contain a consensus sequence for a heparin-binding site, and they are efficiently purified from accessory gland homogenates by heparin-affinity chromatography. No sequence resemblance was found with other proteins in the databases, but their high avidity for heparin suggests a possible involvement of the C proteins in sperm capacitation.