**30. Calmodulin**

amino acids) and a long hydrophobically cysteine-rich domain (84 amino acids). Its steadystate mRNA level accumulated differentially in response to salicylic acid, and to the inocula‐ tion of soybean mosaic virus Sa strain. It responded to drought treatment and salt stress. It

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

SBTX is a 44-kDa basic glycoprotein composed of a 27-kDa polypeptide chain and a 17 kDa polypeptide chain linked by a disulfide bond. The N-terminal sequences of the 44 and 27 kDa chains were identical. The secondary structure content was 35 % alpha-he‐ lix, 13% beta-strand and beta-sheet, 27 % beta-turn, 25 % unordered, and 1 % aromatic residues. SBTX lacked protease-inhibitory and hemagglutinating activities, but was im‐ munologically related to other toxic proteins, such as soyatoxin and canatoxin, and cross-reacted weekly with soybean trypsin inhibitor and agglutinin. It inhibited the growth of *Cercospora sojina*, a fungus causing frogeye leaf spot in soybeans at a concen‐ tration much lower than the lethal dose to mice. Thus it may be useful for the develop‐

Soybean seed ferritin contains a great deal of bioavailable iron and is important for human iron supplementation and prevention of anemia caused by iron deficiency. Dong et al [31] employed a rapid and simple *Escherichia coli* expression system for producing the soybean seed ferritin complex. The two subunits, H-2 and H-1, were encoded in a single plasmid, and optimal expression was accomplished by coexpressing in addition a team of molecular chaperones, trigger factor and GroEL-GroES. The His-tagged ferritin complex was purified by Ni2+ affinity chromatography. An intact ferritin complex was obtained following His-tag‐

Peroxisomal proteins comprise enzymes for metabolite transport, stress response, fatty acid beta-oxidation, the glyoxylate cycle, and photorespiratory glycolate metabolism, an enoyl-CoA hydratase/isomerase family protein, a short-chain dehydrogenase/reductase family protein, 3-hydroxyacyl-CoA dehydrogenase-like protein, and a voltage-dependent anion-se‐

appears that SbPRP plays a defense role in soybean [29].

**27. SBTX, a new toxic protein distinct from soyatoxin**

ment of transgenic plants with augmented resistance to pathogens [30].

**28. Ferritin**

Relationships

248

ged enterokinase digestion [31].

**29. Peroxisomal proteins**

lective channel protein [32].

Calmodulin (CaM) plays a role in defense responses in plants. In soybean, induction of tran‐ scription of calmodulin isoform 4 (GmCaM4) occurred within half an hour following patho‐ gen stimulation. . Park et al utilized the yeast one-hybrid system to isolate two cDNA clones encoding proteins (GmZF-HD1 and GmZF-HD2) which bind to a 30-nt A/T-rich sequence in the GmCaM4 promoter, a region with two repeats of a conserved homeodomain binding site, ATTA. The two proteins are members of the zinc finger homeodomain (ZF-HD) tran‐ scription factor family. A homeodomain motif, but not the two zinc finger domains, is capa‐ ble of binding to the 30-nt GmCaM4 promoter sequence. The interaction between GmZF-HD1 and two homeodomain binding site repeats is subject to regulation by pathogen stimulation. GmZF-HD1 can activate the expression of GmCaM4 through interaction with the two repeats. Thus GmZF-HD1 and GmZF-HD-2 proteins are ZF-HD transcription fac‐ tors that activate GmCaM4 gene expression upon encounter with a pathogen [33].
