PROSITE documentation PDOC00299Microbodies C-terminal targeting signal
Microbodies are a class of small, single membraned organelles to which belong peroxisomes, glyoxysomes, and glycosomes. Microbody proteins are synthesized on free polysomes and imported into the organelle post-translationally. Unlike the import of proteins into mitochondria, chloroplasts or the ER/secretion pathway, import into microbodies does not generally require the removal of a presequence [1]. It has been experimentally shown [2,3,4] that, in some peroxisomal proteins, the targeting signal (PTS) resides in the last three amino acids of the C-terminus. This consensus sequence is known as 'S-K-L' (Ser-Lys-Leu), although some variations are allowed in all three positions. As the peroxisomal targeting signal also seems to be recognized by other microbodies, it is now [1] known as the C-terminal microbody targeting signal (CMTS).
It must be noted that not all microbody proteins contain a CMTS; some seem to contain an internal CMTS-like sequence, but it is not yet known if it is active as such. Finally, a few proteins are synthesized with an N-terminal presequence which is cleaved off during import.
Microbody proteins known or thought to contain a CMTS are listed below.
- Mammalian D-amino acid oxidase.
- Mammalian acyl-coenzyme A oxidase (but not the fungal enzymes).
- Mammalian and yeast (S. cerevisiae) carnitine o-acetyltransferase.
- Mammalian trifunctional fatty acid β oxidation pathway enzyme.
- Mammalian, insect, plants, and Aspergillus uricase.
- Mammalian sterol carrier protein-2 high molecular form (SCP-X).
- Mammalian long chain α-hydroxy acid oxidase.
- Mammalian soluble epoxide hydrolase (sEH).
- Firefly luciferase.
- Plants glycolate oxidase.
- Plants glyoxisomal isocitrate lyase.
- Plants and fungal glyoxisomal malate synthase.
- Trypanosoma glycosomal glucose-6-phosphate isomerase.
- Trypanosoma glycosomal glyceraldehyde 3-phosphate dehydrogenase.
- Yeast (H. polymorpha and Pichia pastoris) alcohol oxidase (AOX).
- Yeast (H. polymorpha) dihydroxy-acetone synthase (DHAS).
- Yeast (S. cerevisiae) catalase A.
- Yeast (S. cerevisiae) citrate synthase.
- Yeast (S. cerevisiae) peroxisomal malate dehydrogenase.
- Yeast (C. boidinii) peroxisomal protein PMP20.
- Yeast (C. tropicalis) hydratase-dehydrogenase-epimerase (HDE) from fatty acid β oxidation pathway.
- Yeast (C. tropicalis) isocitrate lyase.
- Aspergillus niger monoamine oxidase N.
- Candida albicans vacuolar aspartic protease PRA1.
November 1997 / Pattern and text revised.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | De Hoop M.J. Ab G. |
| Source | Biochem. J. 286:657-669(1992). |
| 2 | Authors | Gould S.J. Keller G.-A. Subramani S. |
| Title | Identification of peroxisomal targeting signals located at the carboxy terminus of four peroxisomal proteins. | |
| Source | J. Cell Biol. 107:897-905(1988). | |
| PubMed ID | 2901422 |
| 3 | Authors | Gould S.J. Keller G.-A. Hosken N. Wilkinson J. Subramani S. |
| Title | A conserved tripeptide sorts proteins to peroxisomes. | |
| Source | J. Cell Biol. 108:1657-1664(1989). | |
| PubMed ID | 2654139 |
| 4 | Authors | Gould S.J. Keller G.-A. Schneider M. Howell S.H. Garrard L.J. Goodman J.M. Distel B. Tabak H. Subramani S. |
| Title | Peroxisomal protein import is conserved between yeast, plants, insects and mammals. | |
| Source | EMBO J. 9:85-90(1990). | |
| PubMed ID | 2104803 |
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