Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• glycolipid analogs; scramblase; Introduction Mannosyl phosphoryl dolichol (MPD), an important, multifunctional glycolipid, is used as a mannose donor for protein N-glycosylation, O- and C-mannosylation, and glycosylphosphatidylinositol (GPI) anchoring in the luminal leaflet of the endoplasmic reticulum (ER

• ) [1][2][3][4][5][6][7][8]. Interestingly, MPD is synthesized on the cytoplasmic face of the ER and must be translocated across the ER membrane to participate in luminal glycosyltransfer reactions [3][4]. A specific membrane protein – MPD scramblase – is required to facilitate the transbilayer movement

• of MPD across the ER. Although the activity of MPD scramblase has been described in microsomal vesicles and reconstituted systems [1][2][9], the molecular identity of this protein remains unknown. To circumvent the need for traditional purification strategies to identify the scramblase, we considered