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so how is a threat detected well there
are these pattern recognition receptors
PRRS that can recognize infectious
agents and what they recognize on the
infectious pathogen are structures that
are called pathogen associated molecular
patterns or Pam's P a MP also pattern
recognition receptors as well as
recognizing HAMP's on fallen infectious
agents can recognize structures
associated with damage to our own body
cells and we call these structures
damage associated molecular patterns so
pattern recognition receptors can
recognize both camps and damps and these
can be present on the cell surface or
sometimes inside cells and these may be
on pathogen cells or they may be on our
own body cells what is important to
appreciate is that allo this recognition
is often described as being broadly
specific what is actually being
recognized is recognized in a very very
highly specific way so for example we'll
mention a few pathogen associated
molecular patterns in a few moments one
of them is called lipopolysaccharide or
LPS LPS is found on gram-negative
bacteria and there are lots of different
types of gram-negative bacteria so LPS
is shared between several different
bacteria but the recognition of LPS is
very very highly specific
so recognition is structurally specific
but what is recognized is common to
whole groups of organisms or host cells
these pattern work
mission receptors can be inside cells in
other words intracellular and if they're
interesting though if they're inside a
cell they may be present on the
endosomes within the cell or they may be
present within the cytosol of the cell
alternatively they may be present on the
surface of cells cell surface pattern
recognition receptors or indeed they may
be released or secreted from selves as
soluble pattern recognition receptors
you can now look at a number of
different pattern recognition receptors
and the PAMP that they recognized let's
start with endosomal pattern recognition
receptors there is a group of ten or so
pattern recognition receptors that are
called toll-like receptors a couple of
examples for you now tlr3 toll-like
receptor recognizes the PAMP viral
double-stranded RNA TL r7 and t lr8
recognized vowel single-stranded RNA
whereas T lr9 recognizes a particular
nucleotide sequence within the DNA of
bacteria called bacterial unmethylated
cpg let's now turn to cytosolic pattern
recognition receptors not one nucleotide
binding oligomerization domain
containing protein one and not to these
recognized bacterial peptidoglycan z'
these structures are found on gram
positive bacteria
so again shared between many different
bacteria but the recognition of
peptidoglycan by nod 1 and nod two is
highly specific for that particular
structure rig 1 retinoic acid inducible
gene one recognizes viral
double-stranded RNA and there's a third
example
the cytosolic pattern recognition
receptor nlrp3 not like receptor family
Pilon domain containing 3 which is part
of the inflammasome which we'll discuss
in a few seconds
this recognizes bacterial
lipopolysaccharide LPS cell surface
pattern recognition receptors tlr-2
again recognizes bacterial structures
that are shared between many different
bacterial species various bacterial
lipopeptides and life of proteins tlr4
recognizes bacterial lipopolysaccharide
LPS and tlr5 recognizes bacterial for
the gelling and finally soluble pattern
recognition receptors
mannose binding lectin that recognizes
the sugar mannose as its name suggests
and v : which recognizes n-acetyl
glucosamine another sugar let's now turn
to pattern recognition receptors which
recognize damps damage associated
molecular patterns or sometimes called
danger associated molecular patterns
these are pattern recognition receptors
that recognize structures produced by
our own body cells following damage a
couple of examples of pattern
recognition receptors present on cell
surfaces that recognized amps rage the
receptor for advanced glycation
end-products
as its name suggests recognizes advanced
glycation end products that are produced
by our own cells in response to damage
and h tlr-2 and tlr4 recognized h mg b1
high mobility group box one so if you
were paying attention you will see that
rage recognizes two different damps
advanced glycation end-products and h mg
b one whereas tlr-2 until our four
are specific not for advanced glycation
end-products but 4 h mg b1 and then
finally cytosolic pattern recognition
receptors involved with a structure
called the inflammasome nlrp3 recognizes
the damage or danger associated
molecular pattern uric acid
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