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Figure 1.
Figure 1. Location of T1 domain point mutations. A model of a
Kv channel1 is depicted based on known structures. Only two
subunits on opposite sides of the Kv channel are shown for
clarity. The T1 domain2, 3 is shown to scale below the TM pore
region, which is depicted based on the structure of the KcsA
channel4. An N-terminal inactivation ball structure^1, based on
the NMR structure of the Shaw type Kv channel Kv3.4 (Raw3)
inactivation ball44 is shown to scale connected to one of the T1
subunits. Regions for which no structural information is
available are given as black linking segments (segment A links
the N-terminal inactivation ball to the T1 domain; B is the T1
to S1 linker; C is the S4 to S5 linker and segment D links the
S6 to the C-terminus). S1 -S6 are the proposed Kv, only S5 and
S6 are modeled here. The four-fold symmetry axis at the center
of the hypothetical Kv channel is vertical and indicated by
arrow 1. The backbone conformation of the T1 subunit chain is
shown in color gradually changing from blue (N-terminus) to
white (C-terminus). The model depicts a 'right side up'
relationship between the T1 domain and the transmembrane
domains. An 'upside down' relationship would have the darker
N-terminal regions of the T1 domain near the TM pore region. The
two side chains where mutations have been introduced are
highlighted: Val 135, blue; Asn 136, green. Potential pathways
for ions to reach the TM pore are between the T1 domain and the
TM pore (arrow 2) or up the aqueous central cavity at the axis
of symmetry (arrow 1). The narrowest part of the T1 cavity along
the four fold axis is formed by Asn 136 (green). This figure was
prepared using Setor45.
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