Enzyme-Linked
Membrane
Receptors
Extracellular
ligand-binding
domain
Intracellular
catalytic
domain
*
Most
common
catalytic
domains
have
tyrosine
kinase
activity*
Adds
a
phosphate
group
to
itself
(auto
phosphorylation
->
conformational
change
allowing
binding
+
catalytic
phosphorylation
of
specific
target
proteins
⑨
a
chain
s
a
n
acIds
Adds
a
phosphate
group
to
a
tyrosine
in
specific
target
proteins
⑰N
M
r
rgs,
means
arena
in
me
*
⑳
*Some
catalytic
domains
have
guanyly/cyclase
activity
r
Convert
GTP
to
cGMP,
a
secondary
messenger
Receptor
Tyrosine
Kinases*
Insulin
interacts
with
cellula
receptor
tyrosine
kinase
*
Ligand-binding
domain
Peptide
hormone
that
is
produced
by
B
cells
of
Islets
of
Langerhans
in
pancreas
I
⑰
Reaches
target
cells
(liver,
muscle,
or
fat
cells)
via
bloodstream
Binding
to
receptor
initiates
a
cascade
of
events
(leads
to
increased
Da
a
outside
glucose
uptake
and
metabolism
scan,
no
una
sa
agna
as
an
as
here
Inside
Inability
to
make/sense
Insulin:
Diabetes
Insulin
Receptor:
Glucose
Import
in
Myocytes
⑪Erase
an
in
an
in
an
in
registrich
2
When
insulin
interacts
with
its
receptor,
vesicles
more
to
the
surface
and
fuse
with
the
Insulin
Signaling
Cascade:
Ligand
Binding
plasma
membrane.
Increasing
the
number
of
3
when
insulin
level
drops,
glucose
transporters
In
the
plasma
membrane.
glucose
transporters
are
removed
from
the
plasma
Insulin
binds
to
extracellular
domains
of
receptor
membrane
by
endocytosis
forming
small
vesicles
activates
catalytic
domain
inside
cell
Catalytic
domain
in
one
receptor
phosphorylates
Tyr
-
as
Glucose
residues
in
another
receptor
Receptor
autophosphorylation
allows
binding
and
phosphorylation
of
protein
IRS
-
1
↓
Indirect
Interaction
of
phosphorylated
IRS
with
protein
Bas
Initiates
a
series
of
protein
phosphorylations
ERK;
I
phosphorylated
protein
kinases
enters
nucleus
.
are
inner
in
as
a
s
4
The
smaller
resides
fuse
with
a
larger
Tran scrip tion
factor
(E1K1)
becomes
phosphorylated
+
endosome
Stimulates
expression
of
specific
genes
(e.g.,
glucose
Insulin
levels
rise
again
transporter
(GLUT4C).
