Required for normal production of N-glycosylated proteins in the endoplasmic reticulum (ER). Required for embryonic segmentation, dorsal-ventral patterning and gastrulation. Required for chitin orientation and shaping of the apical and lateral plasma membranes of epidermal cells during cuticle differentiation. Also required for correctly shaping apical membrane topology of the epithelia of other organs such as the midgut and the hindgut. a dolichyl phosphate + UDP-alpha-D-glucose = a dolichyl beta-D-glucosyl phosphate + UDP Protein modification; protein glycosylation. Expressed maternally and zygotically. In cellularizing embryos, maternal expression is ubiquitous. At embryonic stage 11, zygotic expression begins in salivary gland precursor cells. In stage 16 embryos, strong expression in salivary glands and part of the proventriculus is detected. Larval lethality. Embryos lacking maternal and zygotic wol activity show segmentation, dorso-ventral patterning and gastrulation defects. As a result, germband elongation does not proceed normally and mesoderm invagination is disturbed. In these embryos, protein glycosylation is reduced by 25 percent, the ER tubules are smooth and the unfolded protein response (UPR), a transcriptional response which up-regulates genes that enable cells to cope with misfolded, endoplasmic reticulum-retained proteins, is activated. Larvae lacking maternal wol present patterning and morphological defects, including the failure to form a normal head skeleton, a discontinuous cuticle and irregular body contours. Larvae lacking both maternal and zygotic wol show severe reduction in cuticle deposition, a complete failure of denticle formation and melanization, loss of chitin orientation in the procuticle and dislocation of proteins of the lower electron-dense portion of the epicuticle into the upper electron-lucid sublayer. In addition, the midgut microvilli are separated from each other by large gaps and the apical plasma membrane of the hindgut is highly irregular. 'Wollknaeuel' means 'ball of wool' in German. Belongs to the glycosyltransferase 2 family.