soybean trypsin inhibitor (STI)-like domain, beta-trefoil fold, found in class II water-soluble chlorophyll proteins (WSCPs) and similar proteins
There are two kinds of water-soluble chlorophyll (Chl) proteins (WSCPs): Chenopodium-type (Class I, a WSCP from Chenopodium, Atriplex, Polygonum, and Amaranthus species) and Brassica-type (Class II, a WSCP from Brassica, Raphanus, and Lepidium species). Classes I and II WSCPs differ mainly in their photoconvertiblity. Class I WSCPs show a light-induced absorption change, whereas Class II WSCPs do not. This family includes Class II WSCPs. They possess the complete motif of the Kunitz-type proteinase inhibitor but may not inhibit trypsin, whose activity is inhibited strongly by one Kunitz-proteinase inhibitor, the soybean trypsin inhibitor (STI). Members of this subfamily contain a STI-like domain with a beta-trefoil fold, which is characterized by 12 beta strands folded into three similar trefoil subdomains (alpha, beta, and gamma) associated to give an overall structure with pseudo-3-fold symmetry.
Jiyao W et al.(2023). "The conserved domain database in 2023.",