Fig. 2.

OST-dependent and OST-independent cell-free glycoprotein synthesis systems. Membrane-bound OST-dependent glycosylation systems using endogenous (a) and heterologous (b) glycosylation machinery. a Cell-free glycoprotein synthesis systems derived from eukaryotic cell extracts enriched or supplemented with endoplasmic reticulum (ER) microsomes containing glycosylation components. b Cell-free glycoprotein synthesis systems derived from glycoengineered E. coli cells harboring heterologous, membrane-bound glycosylation machinery. c OST-independent glycosylation enzymes are combined with sugar donors in a mix-and-match fashion to make soluble, synthetic glycosylation pathways