There are two distinct cystatins in rice seeds (Oryzacystatin-1 and -2) with different specificities against cysteine proteinases. May be involved in the control of germination by inhibition of endogenous cysteine proteinases. May play a role in defense by inhibiting exogenous proteases such as those present in digestive tracks of insects and nematodes. Expressed in rice seeds from flowering to mature seeds. Belongs to the cystatin family. Phytocystatin subfamily. PubMed:15969500 has erroneously named this protein oryzacystatin-3.