so speaking of some of the things found
in the plasma membrane
it has many different types of proteins
of the different types of proteins there
are two main types
you have integral membrane proteins
which are going to traverse
between the outer and inner leaflet
of the plasma membrane and go through
or integrate or go through the membrane
and then you have peripheral proteins
which sit either
on the inner or the outer
leaflet of the cell these membrane
proteins are going to have a variety of
different functions
there are different proteins that are
allow the plasma membrane to not just
separate our external
and internal environments but also have
multiple
functions including deciding what gets
in and out of the cell so some of these
protein
functions include ion channels which
allow
certain ions to be able to cross from
outside
into the cell or from inside to the
outside of the cell
the reason why we need these is because
ions are positively charged
and therefore cannot pass through that
fatty acid layer
because of the positive charges being
repelled
by the fatty acids another type of
membrane protein function that we find
in our plasma membrane
are carrier proteins similar to the ion
channels these are going to transport
substances
into or out of the cell that cannot just
pass through
on their own a third function
of our membrane proteins are receptor
proteins
now these receptor proteins are going to
do
different things depending on what
happens after
the whatever is being received
binds to the receptor the chemical that
binds the receptor is referred to as a
ligand
and these ligands bind to the receptor
and either are brought into the cell
or sometimes they may trigger other
reactions to occur
a fourth function of the membrane is
enzymatic
so there are several different types of
enzymes that are embedded in our plasma
membrane of our cells
these enzymes are usually bound by a
ligand
and then elicit some type of enzymatic
process after a ligand binds and so in
this way
we think of our plasma membrane not just
as a barrier
but also something that is actively
functioning
to allow certain processes to happen in
our cells
another function of the membrane is
linker proteins
linker proteins are going to link our
cells to
other factors inside and out of the cell
so for example
certain filaments that are associated
with the outside of the cell
or extracellular matrix require linker
proteins
so that the cell is linked to those
different filaments and another function
of the membrane proteins
is cell identity markers so everybody
has cell identity markers on their cells
this is how our body knows that my cells
belong to me
and your cells belong to you they're as
unique to you
as your fingerprints are and these
become
very important when you think about
transplant patients
so for example if i need a heart
transplant and i get a heart
from someone else what's going to happen
is the
cell identity markers on that new heart
will not match the cell identity markers
in the rest of my body
and what happens after that is our
immune system will attack
that new heart because it does not
recognize it as self
and therefore recognizes it as something
that is foreign and must be gotten rid
of
that is why a lot of transparent
patients must
be on immunosuppressive therapy once
they receive a transplant
because of our body's natural defense to
anything that doesn't belong
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