|PROSITE documentation PDOC00092|
Two different types of thiolase [1,2,3] are found both in eukaryotes and in prokaryotes: acetoacetyl-CoA thiolase (EC 220.127.116.11) and 3-ketoacyl-CoA thiolase (EC 18.104.22.168). 3-ketoacyl-CoA thiolase (also called thiolase I) has a broad chain-length specificity for its substrates and is involved in degradative pathways such as fatty acid β-oxidation. Acetoacetyl-CoA thiolase (also called thiolase II) is specific for the thiolysis of acetoacetyl-CoA and involved in biosynthetic pathways such as poly β-hydroxybutyrate synthesis or steroid biogenesis.
In eukaryotes, there are two forms of 3-ketoacyl-CoA thiolase: one located in the mitochondrion and the other in peroxisomes.
There are two conserved cysteine residues important for thiolase activity. The first located in the N-terminal section of the enzymes is involved in the formation of an acyl-enzyme intermediate; the second located at the C-terminal extremity is the active site base involved in deprotonation in the condensation reaction.
Mammalian nonspecific lipid-transfer protein (nsL-TP) (also known as sterol carrier protein 2) is a protein which seems to exist in two different forms: a 14 Kd protein (SCP-2) and a larger 58 Kd protein (SCP-x). The former is found in the cytoplasm or the mitochondria and is involved in lipid transport; the latter is found in peroxisomes. The C-terminal part of SCP-x is identical to SCP-2 while the N-terminal portion is evolutionary related to thiolases .
We developed three signature patterns for this family of proteins, two of which are based on the regions around the biologically important cysteines. The third is based on a highly conserved region in the C-terminal part of these proteins.Last update:
April 2006 / Patterns revised.
PROSITE methods (with tools and information) covered by this documentation:
|1||Authors||Peoples O.P. Sinskey A.J.|
|Title||Poly-beta-hydroxybutyrate biosynthesis in Alcaligenes eutrophus H16. Characterization of the genes encoding beta-ketothiolase and acetoacetyl-CoA reductase.|
|Source||J. Biol. Chem. 264:15293-15297(1989).|
|2||Authors||Yang S.-Y. Yang X.-Y.H. Healy-Louie G. Schulz H. Elzinga M.|
|Title||Nucleotide sequence of the fadA gene. Primary structure of 3-ketoacyl-coenzyme A thiolase from Escherichia coli and the structural organization of the fadAB operon.|
|Source||J. Biol. Chem. 265:10424-10429(1990).|
|3||Authors||Igual J.C. Gonzalez-Bosch C. Dopazo J. Perez-Ortin J.E.|
|Title||Phylogenetic analysis of the thiolase family. Implications for the evolutionary origin of peroxisomes.|
|Source||J. Mol. Evol. 35:147-155(1992).|
|4||Authors||Baker M.E. Billheimer J.T. Strauss J.F. III|
|Title||Similarity between the amino-terminal portion of mammalian 58-kD sterol carrier protein (SCPx) and Escherichia coli acetyl-CoA acyltransferase: evidence for a gene fusion in SCPx.|
|Source||DNA Cell Biol. 10:695-698(1991).|