Characterization of mannosyl transferases during the pupal instar of Stomoxys calcitrans (L)

Particulate fractions (10,000g) from pupae of Stomoxys calcitrans transfer [14C]‐mannose from GDP‐[14C]‐mannose to dolichol monophosphate and proteins. Production of the mannosyl lipid was inhibited by Mn2+, UDP, GMP, GDP, and EDTA. The insect growth regulator diflubenzuron had no effect on mannosyl transferase activity. Dolichol monophosphate and Mg2+ stimulated mannosyl transferase activity. The mannosyl lipid product was identified as mannosyl‐phosphoryl‐dolichol (Man‐P‐Dol). The apparent Km and Vmax values for the formation of Man‐P‐Dol using GDP‐[14C]‐Man while holding dolichol phosphate constant were 2.4 ± 0.9 μM and 9.4 ± 2.3 pmol Man‐P‐Dol·min−1·mg−1 protein, respectively. The apparent Km and Vmax values using dólichol phosphate while holding GDP‐Man constant were 2.2 ± 1.2 μM and 18.5 ± 1.7 pmol Man‐P‐Dol·min−1·mg−1 protein.