title: The Zea mays glycine-rich RNA-binding protein MA16 is bound to a ribonucleotide(s) by a stable linkage.
abstract: Expression of the gene encoding the maize glycine-rich RNA-binding protein MA16 is developmentally regulated and it is involved in environmental stress responses. The MA16 protein shows a wide spectrum of RNA-binding activities. On the basis of in vivo labelling, where a [³²P]phosphate label was linked to the MA16 protein, Freire and Pages (Plant Mol Biol 29:797-807, 1995) suggested that the protein may be post-translationally modified by phosphorylation. However, further analysis showed that the [³²P]phosphate label was sensitive to different treatments, suggesting that modification distinct from protein phosphorylation might occur in the MA16 protein. Biochemical analysis revealed that this [³²P]phosphate labelling was resistant to phenol extraction and denaturing SDS-PAGE but sensitive to micrococcal nuclease, RNase A and RNase T1 treatments. The mobility of [³⁵S] labelled MA16 protein on SDS-PAGE did not significantly changed after the nuclease treatments suggesting that the [³²P]phosphate label associated to MA16 protein could be a ribonucleotide or a very short ribonucleotide chain. In addition, immunoprecipitation of labelled extracts showed that the ribonucleotide(s) linked to the MA16 protein was removed by phosphorolytic activity. This activity could be catalysed by a phosphate-dependent ribonuclease. The C-terminus of MA16 protein harbouring a glycine-rich domain was predicted to be an intrinsically disordered region.
authors.affiliation: Facultad de Ciencias Exactas, Físicas y Naturales, Instituto Multidisciplinario de Biología Vegetal, CONICET, Universidad Nacional de Córdoba, Edificio de Investigaciones Biológicas y Tecnológicas, 5000 Córdoba, Argentina. mig.frei@yahoo.com.ar
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Freire
mesh_terms: D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D003313:Zea mays / Q000378:metabolism*
chemical_list: D006360:Heat-Shock Proteins; D010940:Plant Proteins; C073976:GRP protein, Zea mays