Biology Reference
In-Depth Information
Fig. 4.
Schematic depiction of HAstV nonstructural polyproteins nsP1a
and nsP1b, and proposed proteolytic processing pathway. Predicted trans-
membrane helices (TM), nuclear localization signal (NLS), immunoreactive
epitope (IRE), coiled-coil structures (CC), predicted death domain (DD),
hyper-variable region (HVR), KKXX-like endoplasmic reticulum retention
signal (ER), protease motif, RNA polymerase motif, and putative RNA heli-
case and VPg motifs are shown. Inverted arrowheads denote putative cleav-
age sites dependent on unknown cellular proteases (?), and the viral protease
(pro). White boxes represent intermediate products, while grey boxes repre-
sent the final products. See text for details. Amino acid positions are num-
bered according to HAstV-1 Oxford reference strain (accession no. L23513).
proteases of other plus-stranded RNA viruses, including rabbit hem-
orrhagic disease virus and feline calicivirus,
11
with the substitution of
a serine for a cysteine at the third catalytic amino acid residue (His
461
,
Asp
489
, and Ser
551
). Some of the amino acid residues involved in sub-
strate binding involve Thr
546
and His
566
.
11,46
Several transmembrane helices (TM) have been identified at the
N-terminus of nsP1a. Although the exact number varies among
different studies,
11,20
it is believed that these TMs are responsible for
