title: Nascent pectin formed in Golgi apparatus of pea epicotyls by addition of uronic acids has different properties from nascent pectin at the stage of galactan elongation.
abstract: Microsomal membranes were prepared from etiolated pea (Pisum sativum L.) epicotyls and used to form nascent [Uronic acid-14C]pectin. The enzyme products were characterized by selective enzymic degradation, gel permeation chromatography and analysis of cellulose binding properties. The product obtained had a molecular weight of around 40 kDa, which was significantly lower than that of nascent [Gal-14C]pectin prepared from the same tissues. It is composed mainly of polygalacturonan and perhaps also rhamnogalacturonan (RG-I). Evidence was obtained for the presence of a protein attached to the nascent [Uronic acid-14C]pectin, but it was unaffected by endoglucanase and did not bind to cellulose. Hence, no xyloglucan appeared to be attached to the nascent [Uronic acid-14C]pectin. A model is proposed in which xyloglucan is attached to nascent pectin after formation of homogalacturonan, but before the pectin leaves the Golgi apparatus.
authors.affiliation: Faculty of Sciences, Department of Biology, University of Balamand, Al-Koura, Lebanon. rabdelmassih@balamand.edu.lb
authors.forename: Roula M
authors.initials: RM
authors.lastname: Abdel-Massih
authors.forename: Hind D
authors.initials: HD
authors.lastname: Rizkallah
authors.forename: Rabih Saif
authors.initials: RS
authors.lastname: Al-Din
authors.forename: Elias A-H
authors.initials: EA
authors.lastname: Baydoun
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Brett
mesh_terms: D002845:Chromatography; D005685:Galactans / Q000378:metabolism*; D005936:Glucans / Q000032:analysis / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D006868:Hydrolysis; D008861:Microsomes / Q000378:metabolism; D008954:Models, Biological; D018532:Pisum sativum / Q000201:enzymology / Q000378:metabolism*; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000737:chemistry; D010940:Plant Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014574:Uronic Acids / Q000378:metabolism*; D014990:Xylans / Q000032:analysis / Q000378:metabolism
chemical_list: D005685:Galactans; D005936:Glucans; D010936:Plant Extracts; D010940:Plant Proteins; D014574:Uronic Acids; D014990:Xylans; C029353:xyloglucan; D010368:Pectins