The pest regions containing C-termini of mammalian ornithine decarboxylase and histidine decarboxylase play different roles in protein degradation.

Proteasome 26S must recognize the PEST region-containing C-terminus of mammalian ornithine decarboxylase (ODC) monomer to proceed with degradation. We have detected PEST regions in both termini of mammalian histidine decarboxylase (HDC). In the present report, a chimaeric ODC/HDC was used to elucidate whether the PEST region-containing C-termini of ODC and HDC are exchangeable. Wild-type rat ODC had an expected antizyme and ATP-dependent degradation. This was not the case for both the chimaera and a C-terminus truncated rat ODC. Results suggest that the PEST region-containing C-terminus of rat HDC should have another role different to confering polypeptide availability to the proteasome. Copyright 1999 Academic Press.