García-Maroto F, Maraña C, Mena M, García-Olmedo F, Carbonero P
Cátedra de Bioquímica y Biología Molecular, E.T.S. Ingenieros Agrónomos-UPM, Madrid, Spain.
Plant Mol Biol. 1990 May;14(5):845-53. doi: 10.1007/BF00016517.
We have characterized three cDNA clones corresponding to proteins CM1, CM3 and CM16, which represent the three types of subunits of the wheat tetrameric inhibitor of insect alpha-amylases. The deduced amino acid sequences of the mature polypeptides are homologous to those of the dimeric and monomeric alpha-amylase inhibitors and of the trypsin inhibitors. The mature polypeptides are preceded by typical signal peptides. Southern blot analysis of appropriate aneuploids, using the cloned cDNAs as probes, has revealed the location of genes for subunits of the CM3 and of the CM16 type within a few kb of each other in chromosomes 4A, 4B and 4D, and those for the CM 1 type of subunit in chromosomes 7A, 7B and 7D. Known subunits of the tetrameric inhibitor corresponding to genes from the B and D genomes have been previously characterized. No proteins of this class have been found to be encoded by the A genome in hexaploid wheat (genomes AA, BB, DD) or in diploid wheats (AA) and no anti alpha-amylase activity has been detected in the latter, so that the A-genome genes must be either silent (pseudogenes) or expressed at a much lower level.
我们已鉴定出三个与蛋白质CM1、CM3和CM16相对应的cDNA克隆，它们代表了小麦昆虫α-淀粉酶四聚体抑制剂的三种亚基类型。成熟多肽的推导氨基酸序列与二聚体和单体α-淀粉酶抑制剂以及胰蛋白酶抑制剂的氨基酸序列同源。成熟多肽之前有典型的信号肽。使用克隆的cDNA作为探针，对合适的非整倍体进行Southern印迹分析，结果显示，CM3和CM16类型亚基的基因位于4A、4B和4D染色体上彼此相距几kb的位置，而CM1类型亚基的基因位于7A、7B和7D染色体上。先前已对与B和D基因组基因相对应的四聚体抑制剂的已知亚基进行了表征。在六倍体小麦（基因组AA、BB、DD）或二倍体小麦（AA）中，尚未发现A基因组编码此类蛋白质，并且在后者中未检测到抗α-淀粉酶活性，因此A基因组基因必定要么沉默（假基因），要么表达水平低得多。
