**41. Cysteine proteinase**

Two cDNAs, were isolated from the cotyledons of growing soybean seedlings by cDNA rep‐ resentational difference analysis (cDNA RDA) and rapid amplification of cDNA ends (RACE). Both CysP1 and CysP2 encode a cysteine proteinase (CPR) with a C-terminal KDEL motif. CysP1 and CysP2 were expressed from 6 days to 13 or 14 days after germination in the cotyledons of growing seedlings and in the root, flower and pod of soybean plants [44].

Two types of cysteine proteases, low-specificity enzymes from the papain family and Asnspecific enzymes from the legumin family, are endopeptidases that play a role in the degra‐ dation of seed storage proteins during early growth of seedlings. The action of the enzymes (CPPh1 and LLP, respectively) from the common bean *(Phaseolus vulgaris L.*) on the common bean storage protein phaseolin, and on the homologous soybean storage protein beta-con‐ glycinin, has been examined. The two most active proteinases detected in common bean seedlings individually cannot bring about extensive degradation of phaseolin. However, the successive action of LLP and CPPh1 leads to extensive hydrolysis of phaseolin. CPPh1 ac‐ complished extensive hydrolysis of beta-conglycinin [45].
