In enzymology, a glucomannan 4-beta-mannosyltransferase (EC 2.4.1.32) is an enzyme that catalyzes the chemical reaction

GDP-mannose + (glucomannan)_n ${\displaystyle \rightleftharpoons }$ GDP + (glucomannan)_n+1

Thus, the two substrates of this enzyme are GDP-mannose and (glucomannan)n, whereas its two products are GDP and (glucomannan)n+1, a noncellulosic polysaccharide which is used in the formation of cell walls.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is GDPmannose:glucomannan 1,4-beta-D-mannosyltransferase. Other names in common use include GDP-man-beta-mannan manosyltransferase, and glucomannan-synthase.

• Elbein AD (March 1969). "Biosynthesis of a cell wall glucomannan in mung bean seedlings". The Journal of Biological Chemistry. 244 (6): 1608–16. PMID 4304230.
• "UniProtKB - Q9LZR3 (CSLA9_ARATH)" UniProt database