transporters Flashcards
describe passive diffusion
substance moves down concentration gradient, no proteins required, small uncharged lipophilic molecules
describe facilitated diffusion
substance flows along concentration gradient, proteins required
describe primary active transport
carrier protein required, substance flows against concentration gradient, energy provided by ATP hydrolysis, moves molecules or ions
describe secondary active transport
carrier protein required, substance flows against concentration gradient, energy provided by ATP hydrolysis, gradient of ion used to couple transport, can be symport or antiport
what are the 3 transporter types?
ion transporters and pumps
nutrient/metabolite transporters
neurotransmitter transporters
give examples of ion transporters and pumps
Na-K ATPase
Na/Ca exchangers
give examples of nutrient/metabolite transporters
glucose, nucleosides
give examples of neurotransmitter transporters
monoamines, inhibitory amino acids, excitatory amino acids, ACh, neuroactive peptides
how are neurotransmitters removed from the synaptic cleft?
passive diffusion, enzymatic degradation (peptides and ACh), re-uptake by transporters (monoamine and amino acids)
transporter protein for dopamine neurons?
DAT
transporter protein for noradrenaline neurons?
NET
transporter protein for 5-HT neurons?
SERT
transporter protein for GABA neurons?
GAT-1
transporter protein for ACh neurons?
cholineT
how does the glutamate-glutamine shuttle work?
glutamate released from neurones, uptaken into glial cells via EAATs, converted into glutamine by glutamine synthase, glutamine is expoerted from glia and taken up into neurones where it is converted into glutamate by glutaminase.
what do the vesicular transporters VMAT-1 and VMAT-2 transport?
vesicular amine transporters - 5-HT, dopamine, noradrenaline, histamine
what does the vesicular transporter VAchT transport?
acetylcholine
what does the vesicular transporter VIAAT transport?
glycine/GABA
what do the vesicular transporters Vglut-1, Vglut-2 and Vglut-3 transport?
glutamate
features of epilepsy?
recurrent seizures, caused by burst of electrical activity in brain, causes a temp disruption in normal brain messaging
what are the transporters in epilepsy?
glutamate and GABA transporters
how does tiagabine work as an antiepileptic?
GABA transporter blocker, blocks GABA reuptake so increases levels in synaptic cleft to block seizure initiation
how do SSRIs work?
block 5-HT reuptake into neurones, elevate synaptic levels of 5-HT
how does fenfluramine work as an appetite suppressant?
increases serotonin levels by promoting reverse transport by the reuptake transporter, disrupts vesicular storage
