Biology Reference
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pair has largely similar substrate specificities, which means that even if all of the
mitochondrially shared proteins (Ntg1, Apn1) relocated to the mitochondria, a
basal level of Ntg and Apn activity would remain in the nucleus.
196-198
Each of
these early BER proteins has at least one predicted or confirmed NLS, and
each of the shared proteins contains a predicted or confirmed MTS (
Fig. 3
).
The nuclear protein Ntg2 contains an iron-sulfur center in the C terminus that
may play a role in DNA damage detection and/or allow sensing of the cellular
redox state.
210,211
Various posttranslational modification sites are strongly pre-
dicted for each of these proteins,
including phosphorylation, methylation,
Ntg1
Ntg2
Ung1
Mag1
Ogg1
Apn1
Apn2
NTHL1
Active
Site
CH
3
MTS
NLS
SUMO
PO
4
Palmitoylation
Fe-S
Key
Ub
50 aa
F
IG
. 3. Predicted motifs and posttranslational modification sites in
Saccharomyces cerevisiae
BER proteins and the human Ntg1 homolog NTHL1. The diagram shows the primary sequence
locations of predicted motifs and posttranslational modification sites. Nuclear localization
sequences were predicted using NUCDISC/PSORTII
199
(NLS, orange box); mitochondrial
matrix-targeting sequences used iPSORT
200
and MitoProt
201
(MTS, blue box). The enzyme active
site (yellow box) is as reported in PROSITE. Modification sites were predicted using SUMOsp
2.0,
202
PCI-SUMO,
203
SUMOplot for SUMOylation (SUMO, light green mark); UbPred
204
for
ubiquitination (Ub, red mark); MASA
205
for methylation (CH
3
, purple mark); NetPhosYeast 1.0
206
and Phosida
207
for phosphorylation (PO
4
, light blue mark); CSS-Palm 2.0
208
for palmitoylation
(yellow mark); and Metal Detector
209
for metal-binding sites (Fe-S, green box). Arbitrary score
thresholds were used for each predictor so that only higher-scoring predictions are shown. Ntg1
localization sequences have been experimentally confirmed, and the NLS of Apn1 has been
partially confirmed.
93,94,183
