Spinach chloroplast ATP-dependent endopeptidase: Ti-like protease.

The soluble fraction of spinach chloroplast was used for purification and characterization of an ATP-dependent protease. Purification included Q Sepharose Fast Flow, hydroxylapatite and FPLC Superose 6 column chromatography. The isolated enzyme requires ATP and Mg2+ for stimulation and represents a ubiquitin independent serine protease, containing essential sulphydryl group(s).

Yeast mitochondrial ATP-dependent protease: purification and comparison with the homologous rat enzyme and the bacterial ATP-dependent protease La.

Homogenous ATP-dependent protease has been isolated for the first time from mitochondria of yeast Saccharomyces cerevisiae. The enzyme molecule consists of six 120 kDa subunits. It is a serine protease with an absolute ATP requirement for its activity.

Low translational efficiency of the F1-ATPase beta-subunit mRNA largely accounts for the decreased ATPase content in brown adipose tissue mitochondria.

The half-life of the F1-ATPase beta-subunit (F1-beta) mRNA in ATPase-poor brown adipose tissue (BAT) (t1/2 = 9.5 h) was found to be 3-7-fold shorter than in liver (t1/2 = 27 h) and heart (t1/2 = 63 h) of mice. When translated in reticulocyte lysate, a 2-3-fold lower efficiency appeared with F1-beta mRNA from BAT than from other tissues.

Increased steady-state levels of several mitochondrial and nuclear gene transcripts in rat hepatoma with a low content of mitochondria.

Cells from a rapidly growing rat Zajdela hepatoma were shown to contain (on a protein basis) five-times less mitochondria than hepatocytes from resting or regenerating rat liver. Transcripts of four nuclear genes for representative mitochondrial membrane proteins (beta-F1 subunit and N,N'-dicyclohexyl-carbodiimide-binding protein of ATP synthase, subunit IV of cytochrome oxidase and ADP/ATP translocase) were present in 2-4 times higher amounts in the poly(A)-rich RNA of the hepatoma than in the corresponding RNA fraction from resting or regenerating rat liver. The liver and hepatoma transcripts for the beta-F1 subunit were translated in an in-vitro system with equal efficiency.