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Information on EC 3.5.4.36 - mRNA(cytosine6666) deaminase and Organism(s) Rattus norvegicus and UniProt Accession P38483
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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: Rattus norvegicus
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
apoB mRNA-editing enzyme catalytic polypeptide 1
catalytic subunit of the apoB mRNA editing complex
APOBEC-1
APOBEC1
catalytic component of an RNA-editing complex
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
5-methylcytosine in single-stranded DNA + H2O
thymine in single-stranded DNA + NH3
Apobec1 has 5-methylcytosine deaminase activity, resulting in a thymine base opposite a guanine. If this mismatch is repaired, a methylated cytosine is replaced by an unmethylated one. If it is not repaired, it results in a cytosine -> thymine transition mutation. Apobec1, and perhaps other members of this protein family play a role in epigenetic reprogramming
-
-
?
cytosine in single-stranded DNA + H2O
uracil in single-stranded DNA + NH3
when expressed in bacteria, APOBEC1 can deaminate cytosine in DNA. Its activity on DNA is specific for single-stranded DNA and exhibits dependence on local sequence context
-
-
?
additional information
?
-
APOBEC1 possesses antiviral activity. It is capable of inhibiting the infectivity of various lentiviruses in tissue culture models
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
-
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
mammalian apolipoprotein B (apo B) exists in two forms, each the product of a single gene. The shorter form, apo B48, arises by posttranscriptional RNA editing whereby cytidine deamination produces a UAA termination codon
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
the enzyme specifically catalyzes the deamination of cytidine at position 6666 in apolipoprotein B mRNA to form an uridine. This changes the codon at position 2153 from a genomically encoded CAA (glutamine) to an in-frame stop codon. Apolipoprotein B mRNA editing occurs in the small intestines of all mammals and in the livers of rats, mice, dogs, and horses. Hepatic editing activity is regulated by growth hormone, thyroxine, cortisol, fasting, and diet
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
ASP, a APOBEC-1-stimulating protein, plus APOBEC-1 represent the minimal apoB mRNA editing enzyme in vitro. ASP appears to be associated with the mRNA-binding protein KSRP, which may confer stability to the editing enzyme complex with its substrate apoB RNA
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
the apobec-1 complementation factor (ACF) and apobec-1 comprise the minimal protein requirements for specific and efficient editing of apo-B mRNA in vitro. ACF is also involved in editing in vivo. A model of the enzyme is elaborated in which ACF functions as the RNA-binding subunit that binds to the 11-nucleotide mooring sequence downstream of the editing site and docks apobec-1 to deaminate C6666. The fact that ACF is widely expressed in human tissues that lack apobec-1 and apo-B mRNA suggests that ACF may be involved in other RNA editing or RNA processing events
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
the enzyme is not able to edit apoB RNA in vitro without the addition of complementary or auxiliary proteins
-
-
?
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
5-methylcytosine in single-stranded DNA + H2O
thymine in single-stranded DNA + NH3
Apobec1 has 5-methylcytosine deaminase activity, resulting in a thymine base opposite a guanine. If this mismatch is repaired, a methylated cytosine is replaced by an unmethylated one. If it is not repaired, it results in a cytosine -> thymine transition mutation. Apobec1, and perhaps other members of this protein family play a role in epigenetic reprogramming
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
-
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
mammalian apolipoprotein B (apo B) exists in two forms, each the product of a single gene. The shorter form, apo B48, arises by posttranscriptional RNA editing whereby cytidine deamination produces a UAA termination codon
-
-
?
cytosine6666 in apolipoprotein B mRNA + H2O
uracil6666 in apolipoprotein B mRNA + NH3
the enzyme specifically catalyzes the deamination of cytidine at position 6666 in apolipoprotein B mRNA to form an uridine. This changes the codon at position 2153 from a genomically encoded CAA (glutamine) to an in-frame stop codon. Apolipoprotein B mRNA editing occurs in the small intestines of all mammals and in the livers of rats, mice, dogs, and horses. Hepatic editing activity is regulated by growth hormone, thyroxine, cortisol, fasting, and diet
-
-
?
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Zinc
Zinc
-
zinc binding is required for both apoB RNA editing and cytidine deaminase activity
Zinc
the enzyme contains tightly bound zinc, zinc exhibits a specific role in apoB mRNA editing
Zinc
the zinc finger in p27 may be required for catalysis, protein-protein interactions, or binding to apoB mRNA
Zinc
zinc-dependent enzyme. The amino acids His61, Cys93, and Cys96 chelate zinc
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
physiological function
unlike their human counterparts, APOBEC1 in a wide range of mammalian species may function as a defense mechanism regulating retroelements
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_RAT
229
0
27274
Swiss-Prot
other Location (Reliability: 3)
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
C93S
-
loss of RNA editing activity, great reduction of cytidine deaminase activity
C96S
-
wild-type levels of RNA binding, loss of RNA editing activity, great reduction of cytidine deaminase activity
E63Q
-
wild-type levels of RNA binding, mutation abolishes both cytidine deaminase and RNA editing activity
H61R
-
mutation abolishes RNA binding, loss of RNA editing activity, great reduction of cytidine deaminase activity
additional information
-
mutation of the first four leucines within the heptad repeat of the leucine-rich region (LRR) of apobec-1 results in reduced RNA editing but reservation of wild-type cytidine deaminase activity
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expression of the catalytic subunit of the editing enzyme, p27, in McArdle 7777 cells and in in COS cells. Transfected COS and CHO cells express p27 but lack additional proteins that are required for editing
when the catalytic subunit of the editing enzyme, p27, is expressed in Xenopus oocytes, it requires other proteins to edit apoB mRNA in vitro
expressed in Escherichia coli, as a glutathione S-transferase fusion protein. Overexpression of wild-type apobec-1 in McA 7777 cells results in a 5-6-fold increase in editing of endogenous apoB
-
REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Barnes, C.; Smith, H.C.
Apolipoprotein B mRNA editing in vitro is a zinc-dependent process
Biochem. Biophys. Res. Commun.
197
1410-1414
1993
Rattus norvegicus (P38483)
Navaratnam, N.; Morrison, J.R.; Bhattacharya, S.; Patel, D.; Funahashi, T.; Giannoni, F.; Teng, B.B.; Davidson, N.O., Scott, J.
The p27 catalytic subunit of the apolipoprotein B mRNA editing enzyme is a cytidine deaminase
J. Biol. Chem.
268
20709-20712
1993
Rattus norvegicus (P38483)
Driscoll, D.M.; Zhang, Q.
Expression and characterization of p27, the catalytic subunit of the apolipoprotein B mRNA editing enzyme
J. Biol. Chem.
269
19843-19847
1994
Rattus norvegicus (P38483)
MacGinnitie, A.J.; Anant, S.; Davidson, N.O.
Mutagenesis of apobec-1, the catalytic subunit of the mammalian apolipoprotein B mRNA editing enzyme, reveals distinct domains that mediate cytosine nucleoside deaminase, RNA binding, and RNA editing activity
J. Biol. Chem.
270
14768-14775
1995
Rattus norvegicus
Innerarity, T.L.; Boren, J.; Yamanaka, S.; Olofsson, S.O.
Biosynthesis of apolipoprotein B48-containing lipoproteins. Regulation by novel post-transcriptional mechanisms
J. Biol. Chem.
271
2353-2536
1996
Rattus norvegicus (P38483), Mus musculus (P51908)
Lellek, H.; Kirsten, R.; Diehl, I.; Apostel, F.; Buck, F.; Greeve, J.
Purification and molecular cloning of a novel essential component of the apolipoprotein B mRNA editing enzyme-complex
J. Biol. Chem.
275
19848-19856
2000
Rattus norvegicus (P38483)
Petersen-Mahrt, S.K.; Neuberger, M.S.
In vitro deamination of cytosine to uracil in single-stranded DNA by apolipoprotein B editing complex catalytic subunit 1 (APOBEC1)
J. Biol. Chem.
278
19583-19586
2003
Rattus norvegicus (P38483)
Morgan, H.D.; Dean, W.; Coker, H.A.; Reik, W.; Petersen-Mahrt, S.K.
Activation-induced cytidine deaminase deaminates 5-methylcytosine in DNA and is expressed in pluripotent tissues: implications for epigenetic reprogramming
J. Biol. Chem.
279
52353-52360
2004
Rattus norvegicus (P38483)
Mehta, A.; Kinter, M.T.; Sherman, N.E.; Driscoll, D.M.
Molecular cloning of apobec-1 complementation factor, a novel RNA-binding protein involved in the editing of apolipoprotein B mRNA
Mol. Cell. Biol.
20
1846-1854
2000
Rattus norvegicus (P38483)
Ikeda, T.; Ohsugi, T.; Kimura, T.; Matsushita, S.; Maeda, Y.; Harada, S.; Koito, A.
The antiretroviral potency of APOBEC1 deaminase from small animal species
Nucleic Acids Res.
36
6859-6871
2008
Mesocricetus auratus (Q9EQP0), Mus musculus (P51908), Mustela putorius furo (B2NIW5), Oryctolagus cuniculus (P47855), Rattus norvegicus (P38483)
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