Steroid hormone conjugates function

It can be concluded that the very high sulfokinase activities in the fetus play an important role in the physiological function of active steroids but it is not yet established how these different enzymes are controlled. Xor is it yet known what the biological activity of these steroid conjugates is in this period of life, or how these steroid conjugates are transported, what is their half-life, and how they can be involved in the biological activities of steroid hormones in the fetal compartment. 

The ability of insect sulfotransferases to catalyze the sulfation of plant and insect steroids may simply reflect the broad substrate specificity of the enzymes. On the other hand, it may be indicative of a more important physiological function of the enzymes. Sulfate esters of cholesterol, campesterol and e-sitosterol have been identified in the meconium of tobacco hornworm (M. sexta) pupae ( ), and these steroids are known precursors of a-and e-ecdysone and other molting hormones in this species ( ). Further, there is evidence that houseflies (M. domestica) and diapausing pupae of M. sexta convert 22,25 bisdeoxyecdysone, a-ecdysone and 20-hydroxyecdysone into sulfate and glucoside conjugates ( ). 

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