Agriculture Reference
In-Depth Information
ZZ Domain
The Zinc finger (ZZ) domain is located after the N-terminal PB1 domain. The role
of the ZZ domain in the autophagy pathway is unknown, since the deletion of ZZ
region from the p62 protein did not disturb aggregation of p62 in HeLa cells and
only the PB1 and UBA domains are needed for p62 to form cytoplasmic bodies
required for autophagy clearance (Bjorkoy et al. 2005 ). Nevertheless, in mammals,
the ZZ domain of p62 interacts with RIP1 (receptor-interacting protein) and TRAF6
(TNF receptor associated factor 6)
B pathway (Sanz
et al. 2000 ). In plants, the ZZ domain of Joka2 has been shown to interact with
the tobacco UP9C, a homologue of LSU1, which is implicated in the response to
sulfur deficiency (Wawrzynska et al. 2005 ; Zientara-Rytter et al. 2011 ). Joka2 was
identified in yeast two hybrid search with UP9C (up-regulated by sulfur deficiency)
as a bait using the cDNA library from tobacco ( Nicotiana plumbaginifolia ) seed-
lings grown in nutrient sufficient conditions (Lewandowska et al. 2010 ). Interac-
tions between proteins from both families have been confirmed in planta using
N. tobaccum and Arabidopsis orthologues by bimolecular fluorescence comple-
mentation (BiFC) (K. Zientara-Rytter, A. Sirko - unpublished). Due to the
unknown molecular function of UP9/LSU the role of such binding has yet to be
discovered.
to modulate the NF
ʺ
NBR1/FW Domain
The NBR1/FW domain, (consisting of two sets of three
-strands separated by an
unstructural linker) is located between the ZZ and UBA domains and contains four
highly conserved tryptophan (W) residues. The NBR1/FW domain is present in all
NBR1-like proteins throughout the eukaryotic kingdom (Svenning et al. 2011 ). The
function of the NBR1/FW domain is unknown. However, it has been recently
shown that the mammalian selective autophagy receptor, NBR1, binds to the
light chain of the microtubule-associated protein MAP1B through the NBR1/FW
domain (Marchbank et al. 2012).
ʲ
UBA Domains
The ubiquitin-binding domain (UBA) is short, containing only about 45 residues. It
is a commonly present in many proteins, which are involved in degradation
pathways requiring Ub tagged to the substrate as a signal for its degradation. In
the selective autophagy receptors the UBA domain is located at the C-terminus as a
single domain as in p62 or it could be duplicated as in AtNBR1, Joka2 and other
plant homologues. The UBA domain present in selective autophagy cargo receptors
Search WWH ::




Custom Search