Cloning of cDNA and chromosomal location of genes encoding the three types of subunits of the wheat tetrameric inhibitor of insect ?-amylase

Abstract

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 a-amylases. The deduced amino acid sequences of the mature polypeptides are homologous to those of the dimeric and monomeric a-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 CM1 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 a-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.

Complete amino acid sequence of puroindoline, a new basic and cystine‐rich protein with a unique tryptophan‐rich domain, isolated from wheat endosperm by Triton X‐114 phase partitioning

“…From the SWISS-PROT data bank, such a tryptophan rich domain is unique for a protein. However, a tetrade- [9,10]; a subunit of the exogeneous a-amylase tetrameric inhibitor (CM16) [24,25]; a dimeric exogeneous a-amylase inhibitor (INH 0.19) [23]. Number between cysteine refers to the amino acid length of inserted peptides.…”

Cytokinin oxidase or dehydrogenase?. Mechanism of cytokinin degradation in cereals

“…Protein sequencing of this band produced the sequence SGSCVPGVAFRTNLL that shows 100% alignment with wheat a-amylase/trypsin inhibitor, NCBI GenBank accession no. P17314 [25], so it was clear that the actual CKX was obscured by another protein. SDS/PAGE of the same sample resolved a mixture of four proteins with molecular masses of 38, 40, 58 and 60 kDa.…”

A Multigene Family of Trypsin/α-Amylase Inhibitors from Cereals

“…The complete sequences of WTAI-CMa, WTAI-CMb and WTAI-CMd have been deduced from the corresponding cDNAs (Halford et al, 1988;Medina et al, 1993;Paz-Ares, et al, 1986;Rasmussen and Johansson, 1992). Tetrameric inhibitors have also been characterized in hexaploid wheat Triticum aestivum (genomes AABBDD), as well as in tetraploid Triticum turgidum (AABB) and in diploid Triticum tauschii (DD) and cDNAs corresponding to the three types of subunits have been cloned (García-Maroto et al, 1990).…”

“…Five out of the seven homoeologous chromosome groups carry genes coding for these inhibitors. Genes in the A genome of hexaploid wheats appear to be silenced (pseudogenes) (García-Maroto et al, 1990).…”

“…In wheat and barley the glycosylated forms of WTAI-CM16, BTAICMb and BMAI-1 have been found to be the most prominent allergens, both in vi tro and in vivo (García-Casado et al, 1995;Sanchez-Monge et al, 1992). cDNA clones encoding these three proteins have also been isolated (García-Maroto et al, 1990;Medina et alA993;Mena et al, 1992). …”