36 physiological revision (27 oct) (5- 2 main methods to transduce the sig…
36 physiological revision (27 oct)
1- steroid hormones can diffuse across plasma membrane
3- type 1 nuclear receptore:
not bound in cytoplasm
ormon bind to them translocate into the nucleus
activate transcription inside nuclus
2- type 2 nuc. rece.
in the nuclear in repress
bind them derepressing activation
binding to DNA to activation or repressing
4- cell surface receptors
closed until it binds to a ligand
opens an ion channel
enz. part of the recep. tethered to re.
recepror tyrosin kinases
enz is seperated from the recepror
Gprotein coupled receptors
cant diffuse into the cell
5- 2 main methods to transduce the sig. into the cell
kinase and Gprotein
Kinases puts an enz. onto a prot.
specific like protein kinase
or phorphorylate lots of different pro
phos. changes its stru.and its func
on state when they bound by GTP
Off state when GDP is dephosphorelated
regulated by 2 enz.
GEF: Guanosin Exchange Facor: activating G protein
GAP for switching off : Gtpase activating pro.
hydrolyses the ph. from GTP to GDP
first messenger: hormon , receptor and activator
second messenger: down stream
know the names
transduce in to the cell and activate an effector
effectors can either
increase the activity of the enz
or they can enter the nucleus bind to the DNA and change transcription within the cells
6- protein traffic and secretion
all proteins have a particular tag on them
partucular tag of Amino acids
tags dictate the address
tell the pro where to go
to nucleus : nuclear localisation signal
nuclear proteins get translated on free ribosome in the cytoplasm
NLS is necessary to import into the nucleus
enter the nucleus through nucleur pores: need nuclear pore receptor= importin
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we dont have a big hole
we have 2 membranes to pass
Mt precursser proteins
production begins at the robosomes that are free in the cytoplasm
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we have Endoplasmic Reticulum signal sequence
this gets translated and then we pause
that shuttled into endoplasmic reticulum and
ribosome finds a signal recognition particle
enables it to attache to a receptor that is present on the endoplasmic reticulum
feeds the protein through that receptor
beging translation again
translation pushes the pr. into ER
once complete get shuttled to the golgi complex
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methods that where and how these proteins move around in vesicles
coat proteins are necessary for formation
coat protein one
coat protein 2
clatherin is the one that shuttles from the Golgi complex to the plasma membrane and backwards
put on for formation and drop straight away
only necessary for lift up
where pro goes is determined by Rab
Rab proteins bind to motor proteins that move around on micro tubules or filaments
fusing to the plasma membrane is done by proteins called SNARES
V SNARE = vesicular snare on our viscles= male valcro
after they bind together you can get complete fusion or exocytosis or a pause waiting for signal
T SNARE= female velcro= t= target
anywhere we have a protein embeded in the mem. that assists with th diffu. we call it facilitated difu.
whether difu by channel or transported by carrier mrdisted prot.
carrier mediated : slow process
it needs to bind and have a conformational change and release again
secondary active transport
one of the molec. is transported against its concentration grad. and we are utilising the conc. grad from the other solute