Trafficking of the myrosinase‐associated protein GLL 23 requires NUC / MVP 1/ GOLD 36/ ERMO 3 and the p24 protein CYB

• Published in: The Plant journal : for cell and molecular biology Vol. 77; no. 4; pp. 497 - 510
• Main Authors: Jancowski, Sylwia, Catching, Amanda, Pighin, Jamie, Kudo, Takamasa, Foissner, Ilse, Wasteneys, Geoffrey O.
• Format: Journal Article
• Language: English
• Published: 01-02-2014
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.12408

Proteins detrimental to endoplasmic reticulum (
ER
) morphology need to be efficiently exported. Here, we identify two mechanisms that control trafficking of
A
rabidopsis thaliana
GLL
23, a 43 kDa
GDSL
‐like lipase implicated in glucosinolate metabolism through its association with the β‐glucosidase myrosinase. Using immunofluorescence, we identified two mutants that showed aberrant accumulation of
GLL
23: large perinuclear
ER
aggregates in the
nuclear cage
(
nuc
) mutant; and small compartments contiguous with the peripheral ER in the
cytoplasmic bodies
(
cyb
) mutant. Live imaging of fluorescently tagged GLL23 confirmed its presence in the
nuc
and
cyb
compartments, but lack of fluorescent signals in the wild‐type plants suggested that
GLL
23 is normally post‐translationally modified for
ER
export.
NUC
encodes the
MVP
1/
GOLD
36/
ERM
O3 myrosinase‐associated protein, previously shown to have vacuolar distribution.
CYB
is an
ER
and
G
olgi‐localized p24 type
I
membrane protein component of coat protein complex (
COP
) vesicles, animal and yeast homologues of which are known to be involved in selective cargo sorting for
ER
–
G
olgi export. Without
NUC
,
GLL
23 accumulates in the
ER
this situation suggests that
NUC
is in fact active in the
ER
. Without
CYB
, both
GLL
23 and
NUC
were found to accumulate in
cyb
compartments, consistent with a role for
NUC
in
GLL
23 processing and indicated that
GLL
23 is the likely sorting target of the
CYB
p24 protein.