Synthesis and uptake of cytoplasmically synthesized pyruvate, Pi dikinase polypeptide by chloroplasts
Polyadenylated RNA was isolated from maize leaves and translated in vitro. In agreement with a previous report by others, the authors found among the translation products a 110-kilodalton pyruvate orthophosphate dikinase (PPDK) precursor that is about 16 kilodaltons larger than the polypeptide isolated from cells. This maize PPDK precursor polypeptide was taken up from the translation product mixture by intact spinach chloroplasts and yielded a mature PPDK polypeptide (94 kilodaltons). The uptake and processing support the proposal that the extra 16-kilodalton size of the polypeptide from in vitro translation of maize leaf mRNA represents a transit sequence which is cleaved after its entry into chloroplasts. Moreover, these results provide additional evidence that in vivo in maize leaf cells PPDK polypeptide is synthesized in the cytoplasm and is transported into the chloroplasts. Location of PPDK in C/sub 3/ plant leaves was investigated by immunochemical analysis. A protein blot of stromal protein in each case gave rise to bands corresponding to authentic PPDK polypeptide. This result indicates that PPDK is present in chloroplasts of C/sub 3/ plant leaves as it is in the case of C/sub 4/ plants. 35 references, 3 figures.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6026264
- Journal Information:
- Plant Physiol.; (United States), Vol. 78:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOTRANSFERASES
BIOSYNTHESIS
UPTAKE
CHLOROPLASTS
ENZYME IMMUNOASSAY
LEAVES
MAIZE
MESSENGER-RNA
POLYPEPTIDES
PYRUVIC ACID
SPINACH
WHEAT
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CEREALS
ENZYMES
FOOD
GRASS
IMMUNOASSAY
KETO ACIDS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDES
PHOSPHORUS-GROUP TRANSFERASES
PLANTS
PROTEINS
RNA
SYNTHESIS
TRANSFERASES
VEGETABLES
550200* - Biochemistry