DPM1 is the catalytic subunit of dolichol-phosphate mannose (DPM) synthase complex, catalyzing the transfer of mannose from GDP-mannose to dolichol monophosphate to generate dolichol phosphate mannose (Dol-P-Man) 1. This activated lipid-linked mannose serves as the essential mannosyl donor for N-glycosylation, glycosylphosphatidylinositol (GPI) anchor biosynthesis, and protein O-mannosylation pathways 2. DPM1 functions as part of a three-subunit complex where DPM2 stabilizes DPM1 in the endoplasmic reticulum and enhances its catalytic activity, while DPM3 further stabilizes the complex 1. Beyond canonical glycosylation roles, DPM1 modulates desmosomal adhesion and epidermal differentiation through interactions with SERPINB5, influencing desmoplakin phosphorylation and intercellular junction integrity 3. Mutations in DPM1 cause Congenital Disorder of Glycosylation type 1E (CDG1E), characterized by defective protein glycosylation 2. Notably, DPM1 inhibition can paradoxically rescue DPAGT1 deficiency and ER stress in cellular models, suggesting therapeutic potential for DPAGT1-CDG despite DPM pathway impairment typically causing glycosylation disorders 4.