title: Wheat ribosome-inactivating proteins: seed and leaf forms with different specificities and cofactor requirements.
abstract: Distinct forms of ribosome-inactivating proteins were purified from wheat (Triticum aestivum L.) germ and leaves and termed tritin-S and tritin-L, respectively. These differ in size and charge and are antigenically unrelated. They are both RNA N-glycosidases which act on 26S rRNA in native yeast (Saccharomyces cerevisiae) ribosomes by the removal of A3024 located in a universally conserved sequence in domain VII which has previously been identified as the site of action of ricin A-chain. Tritin-S and tritin-L differ in both their ribosome substrate specificities and cofactor requirements. Tritin-S shows only barely detectable activity on ribosomes from the endosperm, its tissue of synthesis, whereas tritin-L is highly active on leaf ribosomes. Additionally, tritin-S is inactive on wheat germ, tobacco leaf and Escherichia coli ribosomes but active on rabbit reticulocyte and yeast ribosomes. Tritin-L is active on ribosomes from all of the above sources. Tritin-S, unlike tritin-L shows a marked requirement for ATP in its action.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry, West Midlands, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Massiah
authors.forename: M R
authors.initials: MR
authors.lastname: Hartley
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D015180:Electrophoresis, Gel, Two-Dimensional; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology; D010940:Plant Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D011817:Rabbits; D054788:Ribosome Inactivating Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D012639:Seeds / Q000201:enzymology; D013379:Substrate Specificity; D014908:Triticum / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D012335:RNA, Ribosomal; D054789:Ribosome Inactivating Proteins, Type 1; C031676:tritin protein, Triticum aestivum; D000255:Adenosine Triphosphate; D009699:N-Glycosyl Hydrolases; D054788:Ribosome Inactivating Proteins