True Arrestins and Arrestin-Fold Proteins: A Structure-Based Appraisal - Progress in Molecular Biology and Translational Science - page 30

Aly2/ART3 Rod1/ART4 YGR068C/ART5

Ldb9/ART1

Aly1/ART6 Rog3/ART7 Csr2/ART8 Rim8/ART9

YLR392C/ART10 YJL053W/PEP8 YBR250W/SPO23 YPL066W

Figure 2.4 Modeling of the yeast ART and VPS26 families. The structure of S. cerevisiae
ARTs and VPS26 proteins was individually modeled on the Phyre2 web server in the
normal mode. Best templates used for modeling were 1G4M for Ldb9/ART1 (22% cov-
erage, 98% confidence) and YPL066W (47% coverage, 99.4% confidence), 1SUJ for Aly2/
ART3 (31% coverage, 99.9% confidence), Rod1/ART4 (38% coverage, 100% confidence),
YGR068C/ART5 (51% coverage, 100% confidence), Aly1/ART6 (36% coverage, 99.9%
confidence), Rog3/ART7 (43% coverage, 100% confidence), Csr2/ART8 (27% coverage,
99.4% confidence), Rim8/ART9 (54% coverage, 100% confidence), 2R51 for Pep8 (75%
coverage, 100% confidence), 1AYR for YBR250W/SPO23 (58% coverage, 100% confi-
dence). YLR392C/ART10 (68% coverage, 99% confidence) was modeled on multi-
templates (1SUJ, 1G4M, and 2FAU) in the intensive mode. The coverage is rather low
because of important extensions on both sites of the arrestin core for most ARTs.
Ecm21/ART2 could not be modeled. Ribbon structures were generated with PyMOL.
Coloring goes from blue N-terminus to red C-terminus.

ubiquitination. 87 In S. cerevisiae , ART9 (previously known as Rim8) binds
both Rim21, the paralogue of PalH and VPS23, a subunit of the ESCRT-I
subcomplex. Binding of VPS23 proceeds through a SXP 536 motif on Rim8
and the ubiquitin E2 variant domain of VPS23, and recruits in fine the whole
ESCRT-I subcomplex on Rim8. This interaction is essential for Rim sig-
naling. Rim8 itself is monoubiquitinated on K 521 near the SXP motif by
ubiquitin ligase Rsp5 bound to a PKY 508 motif. Overexpressed Rim8
and VPS23 colocalize on cortical punctate structures. 88
The role of ARTs has been demonstrated in the ubiquitination and the
endocytosis of PM transporters targeted to the vacuole for degradation in
response to stress situations or excess of substrate. 10,85,86,89 There are no data
for a possible role of ARTs in cargo recycling.