Golgi transporters: opening the gate to cell wall polysaccharide biosynthesis.

The synthesis of non-cellulosic polysaccharides occurs in the Golgi apparatus and requires a great number of metabolites (substrates and ions). Many enzymes use these substrates to add sugar residues to nascent polysaccharides chains or to introduce methyl and acetyl groups onto these polymers. Most of these metabolites are in the cytosol and their transport to the Golgi lumen is essential for proper polysaccharide biosynthesis. Different transporters activities have been described in Golgi membranes, but many more are thought to be present to provide all the substrates required for polysaccharide biosynthesis and to pump the ions for maintaining ionic homeostasis. Their functional analysis will help us to understand the role these transporters play in cell wall biosynthesis.