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Information on EC 3.5.4.36 - mRNA(cytosine6666) deaminase and Organism(s) Homo sapiens and UniProt Accession P41238
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3.5.4.36 mRNA(cytosine6666) deaminaseIUBMB Comments
The apolipoprotein B mRNA editing enzyme complex catalyses the editing of apolipoprotein B mRNA at cytidine6666 to uridine, thereby transforming the codon for glutamine-2153 to a termination codon. Editing results in translation of a truncated apolipoprotein B isoform (apoB-48) with distinct functions in lipid transport. The catalytic component (APOBEC-1) contains zinc at the active site .
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Word Map
- 3.5.4.36
- cytidine
-
polypeptide-like
-
deamination
- deaminases
-
apobecs
-
hypermutation
-
editosome
-
c-to-u
-
mooring
-
apob48
-
apob100
-
rna-specific
-
unedited
-
mcardle
The taxonomic range for the selected organisms is: Homo sapiens
The expected taxonomic range for this enzyme is: Tetrapoda
The expected taxonomic range for this enzyme is: Tetrapoda
Reaction Schemes
cytosine6666 in apolipoprotein B mRNA
+
=
uracil6666 in apolipoprotein B mRNA
+
Synonyms
apobec-1, apolipoprotein b mrna editing enzyme, apob mrna-editing enzyme catalytic polypeptide 1, apo b messenger rna editing protein, 
more
topSYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
APOBEC1
SYSTEMATIC NAME
IUBMB Comments
mRNA(cytosine6666) aminohydrolase
The apolipoprotein B mRNA editing enzyme complex catalyses the editing of apolipoprotein B mRNA at cytidine6666 to uridine, thereby transforming the codon for glutamine-2153 to a termination codon. Editing results in translation of a truncated apolipoprotein B isoform (apoB-48) with distinct functions in lipid transport. The catalytic component (APOBEC-1) contains zinc at the active site [3].
SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
additional information
?
-
in vitro murine APOBEC1 can extensively edit viral RNA, while human APOBEC1 cannot
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
-
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
APOBEC1, catalytic component of an RNA-editing complex, transports the complementing specificity factor ACF to and from the nucleus as cargo. Expression of APOBEC1 alone edits apoB RNA and generates a substrate for nonsense-mediated decay. The APOBEC1/ACF editing complex protects the edited apoB RNA from nonsense-mediated decay and transports the RNA to the cytoplasm for translation
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
apolipoprotein (apo)B mRNA editing is mediated by a multiprotein editosome complex. Apobec-1 is the catalytic component of this complex. ABBP-1 (apobec-1-binding protein-1) is an apobec-1-interacting protein that may play an important role in apoB mRNA editing
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
for editing to take place, the 27 kDa catalytic subunit of the apoB mRNA-editing enzyme also needs complementing nuclear factors that are expressed in cells that do not normally express or edit apoB mRNA
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
the apolipoprotein B mRNA editing subunit, APOBEC1, has considerable residual enzymatic activity on a minimal apoB mRNA substrate, even in the absence of any auxiliary factors. The effect of the auxiliary factor ACF is to broaden the temperature range of APOBEC1 activity, lowering the optimal temperature and enabling it to function optimally at lower temperatures. A model consistent with this observation is that at lower temperatures ACF promotes a conformational transition in the RNA substrate that occurs spontaneously at higher temperature
-
-
?
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
-
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
APOBEC1, catalytic component of an RNA-editing complex, transports the complementing specificity factor ACF to and from the nucleus as cargo. Expression of APOBEC1 alone edits apoB RNA and generates a substrate for nonsense-mediated decay. The APOBEC1/ACF editing complex protects the edited apoB RNA from nonsense-mediated decay and transports the RNA to the cytoplasm for translation
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
apolipoprotein (apo)B mRNA editing is mediated by a multiprotein editosome complex. Apobec-1 is the catalytic component of this complex. ABBP-1 (apobec-1-binding protein-1) is an apobec-1-interacting protein that may play an important role in apoB mRNA editing
-
-
?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
NaCl
optimal activity of APOBEC1 without auxiliary factor at 80 mM ionic strength, optimal activity of APOBEC1 in presence of the auxiliary factor ACF at 90 mM
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
APOBEC1 complementation factor
broadens the temperature range of APOBEC1 activity, lowers the optimal temperature and enables it to function optimally at lower temperatures, it promotes at lower temperatures a conformational transition in the RNA substrate that occurs spontaneously at higher temperature
-
APOBEC1 complementation factor
required for enzyme-mediated RNA editing
-
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.000000017
cytosine6666 in apolipoprotein B mRNA
30°C, pH 7.0, APOBEC1 in presence of the auxiliary factor ACF
-
0.000000027
cytosine6666 in apolipoprotein B mRNA
41°C, pH 7.0, APOBEC1 in presence of the auxiliary factor ACF
-
0.00000021
cytosine6666 in apolipoprotein B mRNA
30°C, pH 7.5, APOBEC1 without auxiliary factor
-
0.00000022
cytosine6666 in apolipoprotein B mRNA
41°C, pH 7.5, APOBEC1 without auxiliary factor
-
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
UNIPROT
ENTRY NAME
ORGANISM
NO. OF AA
NO. OF TRANSM. HELICES
MOLECULAR WEIGHT[Da]
SOURCE
SEQUENCE
LOCALIZATION PREDICTION
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable).
The reliability class of the localization prediction ranges from 1 (very reliable) to 5 (not reliable). ABEC1_HUMAN
236
0
28192
Swiss-Prot
other Location (Reliability: 3)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
28192
x * 28192, APOBEC-1 from human has proven difficult to purify at levels sufficient for structural studies. Cytosine deaminase from Saccharomyces cerevisiae (CDD1) can be purified readily, which is relevant due to its orthology with APOBEC-1 at the level of both cytidine deaminase (CDA) sequence similarity (27%) and mRNA-editing activity on apolipoprotein B (apoB) substrates. Crystal structure of ScCDD1 is determined to 2.0 A resolution, which reveals that the fundamental CDA fold is necessary and sufficient for C-to-U deamination in pyrimidine metabolism, as well as RNA editing. The data from the CDD1 structure provide the basis for comparative modeling of the APOBEC-1 structure
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
?
x * 28192, APOBEC-1 from human has proven difficult to purify at levels sufficient for structural studies. Cytosine deaminase from Saccharomyces cerevisiae (CDD1) can be purified readily, which is relevant due to its orthology with APOBEC-1 at the level of both cytidine deaminase (CDA) sequence similarity (27%) and mRNA-editing activity on apolipoprotein B (apoB) substrates. Crystal structure of ScCDD1 is determined to 2.0 A resolution, which reveals that the fundamental CDA fold is necessary and sufficient for C-to-U deamination in pyrimidine metabolism, as well as RNA editing. The data from the CDD1 structure provide the basis for comparative modeling of the APOBEC-1 structure
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
characterization of the APOBEC-1 gene and an unusual aberrant splicing pattern of the pre-mRNA
high level expression of APOBEC1 in Sf9 cells as an N-terminal GST fusion protein. Substantial RNA editing activity of APOBEC1 alone may be responsible for the hyperediting observed upon overexpression of APOBEC1 in transgenic mice. These animals develop hepatocellular carcinomas
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Navaratnam, N.; Bhattacharya, S.; Fujino, T.; Patel, D.; Jarmuz, A.L.; Scott, J.
Evolutionary origins of apoB mRNA editing: catalysis by a cytidine deaminase that has acquired a novel RNA-binding motif at its active site
Cell
81
187-195
1995
Homo sapiens (P41238)
Chester, A.; Somasekaram, A.; Tzimina, M.; Jarmuz, A.; Gisbourne, J.; O'Keefe, R.; Scott, J.; Navaratnam, N.
The apolipoprotein B mRNA editing complex performs a multifunctional cycle and suppresses nonsense-mediated decay
EMBO J.
22
3971-3982
2003
Homo sapiens (P41238)
Fujino, T.; Navaratnam, N.; Scott, J.
Human apolipoprotein B RNA editing deaminase gene (APOBEC1)
Genomics
47
266-275
1998
Homo sapiens (P41238), Homo sapiens
Lau, P.P.; Zhu, H.J.; Nakamuta, M.; Chan, L.
Cloning of an Apobec-1-binding protein that also interacts with apolipoprotein B mRNA and evidence for its involvement in RNA editing
J. Biol. Chem.
272
1452-1455
1997
Homo sapiens (P41238), Homo sapiens
Petit, V.; Guetard, D.; Renard, M.; Keriel, A.; Sitbon, M.; Wain-Hobson, S.; Vartanian, J.P.
Murine APOBEC1 is a powerful mutator of retroviral and cellular RNA in vitro and in vivo
J. Mol. Biol.
385
65-78
2008
Homo sapiens (P41238), Mus musculus (P51908)
Xie, K.; Sowden, M.P.; Dance, G.S.; Torelli, A.T.; Smith, H.C.; Wedekind, J.E.
The structure of a yeast RNA-editing deaminase provides insight into the fold and function of activation-induced deaminase and APOBEC-1
Proc. Natl. Acad. Sci. USA
101
8114-8119
2004
Homo sapiens (P41238)
Chester, A.; Weinreb, V.; Carter, C.W.Jr.; Navaratnam, N.
Optimization of apolipoprotein B mRNA editing by APOBEC1 apoenzyme and the role of its auxiliary factor, ACF
RNA
10
1399-1411
2004
Homo sapiens (P41238)
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