heat-bleached oat ( avena sativa l. cv porter ) leaves lacking 70s chloroplast ribosomes have been used to demonstrate that four chloroplast-localized enzymes of pyrimidine nucleotide biosynthesis : aspartate carbamoyl-transferase , dihydroorotase , orotidine phosphoribosyl-transferase , and orotidine-5'-phosphate decarboxylase , are synthesized on cytoplasmic ribosomes .
C0010834
cytoplasmic
C0035553
ribosomes