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PROSITE documentation PDOC00299 |
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.
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 |