Mau S L, Chen C G, Pu Z Y, Moritz R L, Simpson R J, Bacic A, Clarke A E
CRC for Industrial Plant Biopolymers and Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria, Australia.
Plant J. 1995 Aug;8(2):269-81. doi: 10.1046/j.1365-313x.1995.08020269.x.
This paper reports the isolation of cDNAs encoding the protein backbone of two arabinogalactan-proteins (AGPs), one from pear cell suspension cultures (AGPPc2) and the other from suspension cultures of Nicotiana alata (AGPNa2). The proteins encoded by these cDNAs are quite different from the 'classical' AGP backbones described previously for AGPs isolated from pear suspension cultures and extracts of N. alata styles. The cDNA for AGPPc2 encodes a 294 amino acid protein, of which a relatively short stretch (35 amino acids) is Hyp/Pro rich; this stretch is flanked by sequences which are dominated by Asn residues. Asn residues are not a feature of the 'classical' AGP backbones in which Hyp/Pro, Ser, Ala and Thr account for most of the amino acids. The cDNA for AGPNa2 encodes a 437 amino acid protein, which contains two distinct domains: one rich in Hyp/Pro, Ser, Ala, Thr and the other rich in Asn, Tyr and Ser. The composition and sequence of the Pro-rich domain resembles that of the 'classical' AGP backbone. The Asn-rich domains of the two cDNAs described have no sequence similarity; in both cases they are predicted to be processed to give a mature backbone with a composition similar to that of the 'classical' AGPs. The study shows that different AGPs can differ in the amino acid sequence in the protein backbone, as well as the composition and sequence of the arabinogalactan side-chains. It also shows that differential expression of genes encoding AGP protein backbones, as well as differential glycosylation, can contribute to the tissue specificity of AGPs.
本文报道了编码两种阿拉伯半乳聚糖蛋白（AGP）蛋白质骨架的cDNA的分离，一种来自梨细胞悬浮培养物（AGPPc2），另一种来自烟草悬浮培养物（AGPNa2）。这些cDNA编码的蛋白质与先前从梨悬浮培养物和烟草花柱提取物中分离出的AGP所描述的“经典”AGP骨架有很大不同。AGPPc2的cDNA编码一个294个氨基酸的蛋白质，其中相对较短的一段（35个氨基酸）富含Hyp/Pro；这段序列两侧是主要由Asn残基组成的序列。Asn残基不是“经典”AGP骨架的特征，在“经典”AGP骨架中，Hyp/Pro、Ser、Ala和Thr占大多数氨基酸。AGPNa2的cDNA编码一个437个氨基酸的蛋白质，它包含两个不同的结构域：一个富含Hyp/Pro、Ser、Ala、Thr，另一个富含Asn、Tyr和Ser。富含Pro的结构域的组成和序列类似于“经典”AGP骨架。所描述的两个cDNA的富含Asn的结构域没有序列相似性；在这两种情况下，预计它们会被加工成具有与“经典”AGP相似组成的成熟骨架。该研究表明，不同的AGP在蛋白质骨架的氨基酸序列以及阿拉伯半乳聚糖侧链的组成和序列上可能存在差异。它还表明，编码AGP蛋白质骨架的基因的差异表达以及差异糖基化可以导致AGP的组织特异性。
