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- *******************************************
- * Microbodies 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 trifunctional fatty acid beta oxidation pathway enzyme.
- - Mammalian, insect, plants, and Aspergillus uricase.
- - Mammalian sterol carrier protein-2 high molecular form (SCP-X).
- - Mammalian long chain alpha-hydroxy acid oxidase.
- - Mammalian soluble epoxide hydrolase (sEH).
- - Firefly luciferase.
- - Plants glycolate oxidase.
- - Plants glyoxisomal isocitrate lyase.
- - Plants 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) carnitine o-acetyltransferase.
- - 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 beta oxidation pathway.
- - Yeast (C. tropicalis) isocitrate lyase.
-
- -Consensus pattern: [SAGCN]-[RKH]-[LIVMAF]>
- -Last update: June 1994 / Pattern and text revised.
-
- [ 1] De Hoop M.J., Ab G.
- Biochem. J. 286:657-669(1992).
- [ 2] Gould S.J., Keller G.-A., Subramani S.
- J. Cell Biol. 107:897-905(1988).
- [ 3] Gould S.J., Keller G.-A., Hosken N., Wilkinson J., Subramani S.
- J. Cell Biol. 108:1657-1664(1989).
- [ 4] Gould S.J., Keller G.-A., Schneider M., Howell S.H., Garrard L.J.,
- Goodman J.M., Distel B, Tabak H., Subramani S.
- EMBO J. 9:85-90(1990).
-