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Microbiology Essay plans > More GTPases > Flashcards

More GTPases Flashcards

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Biology 101 flashcards
1
Q

Ran

A

small GTPases which is a molecular switch involved in nuclear transport - karyopherins

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2
Q

Karyopherins in the cytosol

A

-do not bind Ran.GDP so they are free to bind cargo

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3
Q

Ran GTP in the nucleus

A

the karyopherin cargo encounters Ran GTP and is transported back to the cytosol

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4
Q

GAP and GEF in the nuclear exchange importance

A

GAP is present in the cytosol - mainly Ran.GDP here

GEF is present in the Nucleus - RanGTP mainly here

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5
Q

what frees the karyopherin from ran.GTP when it is returned to the cytosol

A

encountering GAP - changing it to Ran.GDP which the karyopherin won’t bind

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6
Q

what happen to RanGDP when it is freed from karyopherin

A

is transported back to the nucleus through its own nuclear transport receptor, and converted back to RanGTP by GEF

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7
Q

Nuclear transport occurs when

A

specific proteins interact with karyopherins in a ran.GTP dependent manor

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8
Q

what does SRP stand for

A

signal recognition peptide

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9
Q

GPRCs

A

7TM domains, change 3D structure when ligand binds, trimeric - act on GEFs to exchange GDP –>GTP

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10
Q

GPRCs - a and y

A

a and y membrane bound by lipid tails

a either bound to GTP or GDP, activation of a - dissociates from b and y and then binds independent targets

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11
Q

a subunit of GPRC as a GTPase

A

hydrolyses GTP, causes a to dissociate from target protein + recombine with BY

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12
Q

Gas

A

activates adenylate cyclase - cytomplasmin cAMP conc. is normally v low - signal turned off by phosphodiesterase

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13
Q

cAMP mediates effects via

A

PKA - phosphorylates target proteins
FAST - phosphodiesterase to ensure cAMP acts as switch
SLOW - CREB bind CRB and CRE elements on DNA upstream of target genes - target transcription

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14
Q

GPRCs coupled to Gaq

A

activate membrane bound PLC - Beta

which then acts on phosphoinositol 4,5 biphosphate - PI(4,5)P2

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15
Q

PI(4,5)P2

A

the least abundant phosphinositide in the PM (<10%)
cleaved into DAG and IP3
diacyglycerol and inositol triphosphate

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16
Q

DAG - diacylglycerol

A

stays in the membrane, immediately binds to PKC bringing it to the membrane

17
Q

IP3 - inositol 3,4,5 triphosphate

A

interacts with the ER and relates calcium, IP3 binds gated Ca2+ ion channel in ER membrane - increases Ca2+ in cytosol - Ca2+ binds to the PKC - phosphorylates target proteins

18
Q

not all PKCs require

A

calcium - this pathway does (Gq)

19
Q

cell responses which GPCRs activate PLCb

A

liver - vasopressin - glycogen breakdown

smooth muscle - acetylcholine - muscle contraction

20
Q

uses Ca2+

A
  • signal during fertilisation - egg activation
  • muscle cells - contraction
  • heart
21
Q

how is cytosolic calcium maintained at 10^-7

A
  • Ca2+ in the ER membrane
  • Ca2+ binding molecules in the cytosol
  • active Ca2+ transport in the mitochondrial matrix
22
Q

wat is Cam

A

a kinase which recognises Ca2+ spike in the heart

Ca2+/Cam kinase II initially activated by Ca2+/Cam undergoes autophosphorylation - even when Ca2+ signal lost , kinase remains - until phosphatase overwhelms

23
Q

2 classes which transmit signals from RTKs

A

Rho and ras

24
Q

RTK anchored to

A

the cytoplasmic face of the plasma membrane

25
Q

RTK docking proteins

A

Grb2 and Drk bind to pTyr on receptor - brings Ras-GEF to PM - activating Ras

26
Q

Ras

A

associates and activates a kinase - triggering MAP kinase cascade - results in phosphorylation of target proteins + cellular response

27
Q

Map stands for

A

mitogen activated proteins

28
Q

Negative feedback w. RTK - ras

A

activation of phosphatase and MAPK - dependent inactivation of Raf

29
Q

scaffolding and docking proteins are activated by

A

small GTPase

30
Q

what do GPRCs and RTKs lead to

A

gene regulation and target proteins

Microbiology Essay plans (9 decks)

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