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Field | Value |
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Namespace | Biological process |
Short description | CAAX-box protein maturation |
Full defintion | A series of specific posttranslational modifications to the CAAX box region of CAAX box proteins. CAAX box proteins are eukaryotic proteins that contain a CAAX motif where the C is a cysteine, the two A residues are aliphatic amino acids and the X can be one of several amino acids. The CAAX-box proteins undergo three sequential, enzymatic, post-translational modifications essential to their targeting: First, the proteins are prenylated by one of two prenyltransferases called farnesyltransferase and geranylgeranyltransferase-I. Prenylation results in the covalent attachment of either farnesyl or geranylgeranyl isoprenoid groups to the cysteine in the CAAX box motif. Prenylation is followed by proteolytic removal of the last three amino acids of the protein (AAX). Finally, the newly exposed carboxylate group of the isoprenylcysteine is methylated by an ER-associated prenyl-dependent carboxylmethyltransferase. |
Subterm of |
The relationship of GO:0080120 with other GO terms.
Relationship type | GO terms |
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Is a | |
Regulates | n.a. |
Part of | n.a. |
Positively regulates | n.a. |
Negatively regulates | n.a. |
A force layout showing the ancestor tree for GO:0080120, and its immediate children. If you wish to explore the tree dynamically, please use the GO Explorer.
This table contains additional metadata associated with the GO entry's definition field.
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PMID | Functional analysis of Arabidopsis postprenylation CaaX processing enzymes and their function in subcellular protein targeting. Plant Physiol. 2008 Sep; 148 (1): 119–31.PMID: 18641086 Prenylation is a posttranslational protein modification essential for developmental processes and response to abscisic acid. Following prenylation, the three C-terminal residues are proteoliticaly removed and in turn the free carboxyl group of the isoprenyl cysteine is methylated. The proteolysis and methylation, collectively referred to as CaaX processing, are catalyzed by Ste24 endoprotease or Rce1 endoprotease and by an isoprenyl cysteine methyltransferase (ICMT). Arabidopsis (Arabidopsis thaliana) contains single STE24 and RCE1 and two ICMT homologs. Here we show that in yeast (Saccharomyces cerevisiae) AtRCE1 promoted a-mating factor secretion and membrane localization of a ROP GTPase. Furthermore, green fluorescent protein fusion proteins of AtSTE24, AtRCE1, AtICMTA, and AtICMTB are colocalized in the endoplasmic reticulum, indicating that prenylated proteins reach this compartment and that CaaX processing is likely required for subcellular targeting. AtICMTB can process yeast a-factor more efficiently than AtICMTA. Sequence and mutational analyses revealed that the higher activity AtICMTB is conferred by five residues, which are conserved between yeast Ste14p, human ICMT, and AtICMTB but not in AtICMTA. Quantitative real-time reverse transcription-polymerase chain reaction and microarray data show that AtICMTA expression is significantly lower compared to AtICMTB. AtICMTA null mutants have a wild-type phenotype, indicating that its function is redundant. However, AtICMT RNAi lines had fasciated inflorescence stems, altered phylotaxis, and developed multiple buds without stem elongation. The phenotype of the ICMT RNAi lines is similar to farnesyltransferase beta-subunit mutant enhanced response to abscisic acid2 but is more subtle. Collectively, the data suggest that AtICMTB is likely the major ICMT and that methylation modulates activity of prenylated proteins. |
GO predictions are based solely on the InterPro-to-GO mappings published by EMBL-EBI, which are in turn based on the mapping of predicted domains to the InterPro dataset. The InterPro-to-GO mapping was last updated on , while the GO metadata was last updated on .