Role of cysteine in the dietary control of the expression of 3-phosphoglycerate dehydrogenase in rat liver.

Shifting rats to a protein-free, carbohydrate-rich diet, although not starvation, resulted in the appearance of mRNA for, and activity of, 3-phosphoglycerate dehydrogenase (3-PGDH) in liver as well as in a marked decrease in plasma cystine concentration. Refeeding with protein caused a 50% decrease in the mRNA in 8 h and its complete disappearance within 24 h, followed by a slower disappearance of the enzymic activity. Intraperitoneal administration of cysteine or methionine to protein-starved rats decreased the mRNA by 50-60% after 8 h.

Cloning, sequencing and expression of rat liver 3-phosphoglycerate dehydrogenase.

Rat liver d-3-phosphoglycerate dehydrogenase was purified to homogeneity and digested with trypsin, and the sequences of two peptides were determined. This sequence information was used to screen a rat hepatoma cDNA library. Among 11 positive clones, two covered the whole coding sequence.

Cloning and sequencing of rat liver carboxylesterase ES-4 (microsomal palmitoyl-CoA hydrolase).

A cDNA which encodes a carboxylesterase of 561 amino acid residues including a cleavable signal peptide is described. The enzyme expressed in COS cells migrates during PAGE (SDS-, and non-denaturing) as a single prominent band in the region of liver ES-4. It ends in the C-terminal cell-retention signal -HNEL, which, in COS cells overexpressing the enzyme, appears to be slightly less efficient than the signals -HTEL and -HVEL of ES-3 and ES-10 respectively.

Cloning and sequencing of rat liver carboxylesterase ES-3 (egasyn).

The cDNA of the rat carboxylesterase ES-3 encodes a polypeptide with 561 amino acid residues including a cleavable signal peptide at the N-terminus. The processed polypeptide shows over 90% sequence identity to mouse egasyn (ES-22); its calculated pI (5.5) matches the value determined for purified liver ES-3.