LMPD Database

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LMP011163

UniProt Annotations

Entry Information
Gene NameS-isoprenylcysteine O-methyltransferase B
Protein EntryICMTB_ARATH
UniProt IDQ93W54
SpeciesArabidopsis
Comments
Comment typeDescription
Biophysicochemical PropertiesKinetic parameters: KM=5.0 uM for AFC as methyl acceptor {ECO:0000269|PubMed:12472689}; KM=3.0 uM for AGGC as methyl acceptor {ECO:0000269|PubMed:12472689}; Vmax=220 pmol/min/mg enzyme toward AFC as methyl acceptor {ECO:0000269|PubMed:12472689}; Vmax=296 pmol/min/mg enzyme toward AGGC as methyl acceptor {ECO:0000269|PubMed:12472689};
Catalytic ActivityS-adenosyl-L-methionine + protein C-terminal S-farnesyl-L-cysteine = S-adenosyl-L-homocysteine + protein C- terminal S-farnesyl-L-cysteine methyl ester.
CofactorName=Zn(2+); Xref=ChEBI:CHEBI:29105; Evidence={ECO:0000250}; Note=Divalent metal cations. Probably Zn(2+). {ECO:0000250};
Disruption PhenotypePlants lacking ICMTA and ICMTB have altered phyllotaxis, fasciated stems and development of axillary flowers. {ECO:0000269|PubMed:18641086}.
Enzyme RegulationInhibited by farnesylthioacetic acid (FTAA) and N-acetyl-S-trans, trans-farnesyl-l-cysteine (AFC).
FunctionCatalyzes the post-translational methylation of isoprenylated C-terminal cysteine residues, resulting in the modulation of the function of prenylated proteins. Involved in negative regulation of abscisic acid signaling. Carboxyl methylation is a reversible and potentially regulated step in the post-translational modification of prenylated proteins. {ECO:0000269|PubMed:12472689, ECO:0000269|PubMed:18957507}.
InductionNot induced by abscisic acid or auxin. {ECO:0000269|PubMed:18957507}.
MiscellaneousICMTB is more widely expressed and has a higher catalytic activity than ICMTA.
Sequence CautionSequence=CAC08334.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305};
SimilarityBelongs to the class VI-like SAM-binding methyltransferase superfamily. Isoprenylcysteine carboxyl methyltransferase family. {ECO:0000305}.
Subcellular LocationEndoplasmic reticulum membrane {ECO:0000269|PubMed:18641086}; Multi-pass membrane protein {ECO:0000269|PubMed:18641086}.
Tissue SpecificityExpressed in flowers, stems, leaves, roots and siliques. Detected in apices and vascular tissues of leaves and roots, in the stigma and in the filaments and anthers of stamen. Not found in petioles or hypocotyls. {ECO:0000269|PubMed:12472689}.