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Aquaporine

Aquaporine, often spelled aquaporin, refers to a family of integral membrane proteins that form channels specialized for water transport across cell membranes. They are found in bacteria, plants, and animals and regulate osmoregulation and hydration. Some members also conduct small solutes such as glycerol, in which case they are called aquaglyceroporins.

Structure and mechanism: Each aquaporin monomer folds into six helices and assembles as a tetramer in the

Function and regulation: Water transport via aquaporins follows osmotic gradients and is typically faster than simple

Diversity and distribution: Humans express thirteen aquaporins (AQP0–AQP12) with tissue-specific patterns, including AQP1 in kidney and

Clinical relevance: Altered aquaporin function can cause disease. AQP2 mutations cause nephrogenic diabetes insipidus; AQP0 defects

Discovery and nomenclature: Aquaporins were identified in 1992 by Peter Agre and colleagues, who later shared

membrane.
The
pore
of
each
subunit
is
formed
by
conserved
NPA
motifs
and
a
narrow
ar/R
constriction
that
selects
water
and
excludes
ions.
This
architecture
enables
rapid,
regulated
water
flow
down
osmotic
gradients.
diffusion.
Activity
is
controlled
by
trafficking
to
the
membrane,
gating,
and
phosphorylation
in
certain
isoforms.
In
plants,
aquaporins
modulate
root
uptake
and
leaf
water
status;
in
animals,
they
contribute
to
kidney
concentrating
ability
and
tissue
hydration.
brain,
AQP2
in
collecting
ducts,
AQP4
in
brain,
and
AQP0
in
the
lens.
Plants
and
microbes
possess
numerous
aquaporins
categorized
into
subfamilies.
are
linked
to
cataracts;
AQP4
has
a
role
in
brain
water
homeostasis
and
neuromyelitis
optica.
Research
explores
aquaporin-targeted
therapies
for
edema
and
ocular
conditions.
the
Nobel
Prize
in
Chemistry
in
2003
for
work
on
membrane
channels.
The
term
aquaporin
reflects
water
transport
(aqua)
and
pores
(porin).