Page 151 - The Miracle of Hormones

Communication Within The Cell

Now, in order to observe an example of this harmony, let us exam-
ine the communication mechanism that goes into action to repair the area
where a person has cut his hand. In this situation, a messenger molecule
called "platelet derived growth factor" (PDGF) unites with the receptor of
the smooth muscle cell in the blood vessel that has received the damage.
As a result of this union, the tail of the receptor inside the cell binds to a
protein called Grb2. Grb2 is a messenger protein formed from the union
of SH2 and SH3 particles; in order to establish communication among

What happens when a hormone combines with a receptor?

Tyrosine (receptor)

The messenger hormone
combines with "tyrosine
GDP
Inactive Ras kinase"(the cell's recep-
tor)

As a result of the combination,
the end of the receptor inside the
Sos SH3
cell binds to the Grb2 protein,
Grb2
which is responsible for commu-
nication among proteins. After
this, Grb2 binds to the communi-
cation protein Sos.
Active Ras

SOS activates another protein
called Ras. As a result of these
Sos SH3 operations (and often several oth-
Grb2
ers), a message is transmitted to
the relevant genes in the DNA.
Signaling

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