A Saporin‐6 cDNA containing a precursor sequence coding for a carboxyl‐terminal extension

Abstract
Saporin-6 is a single-chain ribosome inactivating protein (RIP) from the seeds and the leaves of Saponaria officinalis (Caryophyllaceae). Here we have identified the COOH-terminal end of mature Saporin-6 and, by cDNA sequencing, the predicted carboxyl-terminal sequence of a leaf saporin-6 primary translation product. Our data indicate that the characterized cDNA codes for a precursor contiaing a 22 amino acid carboxyl-terminal extension, not present in mature Saporin-6, that shows similarity to carboxyl-terminal propeptides of vacuolar proteins, suggesting that it may be involved in protein trafficking.