This entry represents a group of sugar methyltransferases found in plants and bacteria, including protein IRREGULAR XYLEM IRX15/IRX15L, glucuronoxylan 4-O-methyltransferases 1-3 (GXM1-3) and AMG1/2 (probable methyltransferase At1g27930 and At1g67330, respectively) from Arabidopsis [6]. GXMs and IRX15/15L are all expressed in secondary wall-forming cells and they are all involved in xylan biosynthesis. However, they have different functions [1,2,6]. IRX15/IRX15L are required for xylan biosynthesis and/or xylan deposition, although their enzymatic activity is unknown [3,4,6]. GXMs catalyse the 4-O-methylation of the glucuronic acid substituent on xylan [1,2,5,6]. This entry also includes AGM1 (also known as probable methyltransferase At1g27930) and AGM2 (At1g67330) which are required for 4-O-methylation of glucuronic acid of arabinogalactan proteins, a different plant cell wall component [6].

1: Modification of the degree of 4-O-methylation of secondary wall glucuronoxylan. Yuan Y, Teng Q, Lee C, Zhong R, Ye ZH; Plant Sci. 2014;219:42-50. PMID:24576763

2: Three Arabidopsis DUF579 domain-containing GXM proteins are methyltransferases catalyzing 4-o-methylation of glucuronic acid on xylan. Lee C, Teng Q, Zhong R, Yuan Y, Haghighat M, Ye ZH; Plant Cell Physiol. 2012;53:1934-1949. PMID:23045523

3: Arabidopsis genes IRREGULAR XYLEM (IRX15) and IRX15L encode DUF579-containing proteins that are essential for normal xylan deposition in the secondary cell wall. Brown D, Wightman R, Zhang Z, Gomez LD, Atanassov I, Bukowski JP, Tryfona T, McQueen-Mason SJ, Dupree P, Turner S; Plant J. 2011; 0:0-0. PMID:21251108

4: The DUF579 domain containing proteins IRX15 and IRX15-L affect xylan synthesis in Arabidopsis. Jensen JK, Kim H, Cocuron JC, Orler R, Ralph J, Wilkerson CG; Plant J. 2011; 0:0-0. PMID:21288268

5: 4-O-methylation of glucuronic acid in Arabidopsis glucuronoxylan is catalyzed by a domain of unknown function family 579 protein. Urbanowicz BR, Pena MJ, Ratnaparkhe S, Avci U, Backe J, Steet HF, Foston M, Li H, O'Neill MA, Ragauskas AJ, Darvill AG, Wyman C, Gilbert HJ, York WS; Proc Natl Acad Sci U S A. 2012;109:14253-14258. PMID:22893684

6: Two members of the DUF579 family are responsible for arabinogalactan methylation in Arabidopsis. Temple H, Mortimer JC, Tryfona T, Yu X, Lopez-Hernandez F, Sorieul M, Anders N, Dupree P; Plant Direct. 2019;3:e00117. PMID:31245760