MEMBRANE TRANSPORT
A membrane protein remains closed until the membrane potential reaches -55 mV. The channel then rapidly opens, allowing Na⁺ influx. What type of transport?
What is Voltage-Gated Channel?
A membrane protein spans the membrane seven times and activates heterotrimeric G proteins following ligand binding.
During translation, this molecule acts as the adaptor that matches mRNA codons to their correct amino acids.
What is tRNA?
Coat protein to direct in recycle ER-resident proteins back to the ER.
What is COP1?
When a neurotoxin blocks ATP production, neurons gradually lose their membrane voltage because the ion gradients can no longer be sustained. (Which membrane transport cannot maintain resting membrane potential?)
What is Sodium-Potassium Pump?
Glucose enters intestinal epithelial cells against its concentration gradient without directly hydrolyzing ATP. Instead, it uses the energy stored in a sodium gradient established by the sodium-potassium pump.
Following activation of Gs, this membrane-associated enzyme converts ATP into a second messenger that activates protein kinase A.
A membrane-embedded lipid carrier assembles an oligosaccharide in the ER before transferring it onto a growing polypeptide.
This coat protein participates in receptor-mediated endocytosis and transport of lysosomal enzymes from the trans-Golgi network.
What is clathrin?
Activation of a receptor tyrosine kinase causes sequential phosphorylation of RAF, MEK, and ERK, greatly amplifying an extracellular signal.
What is MAP Kinase Cascade?
A membrane protein moves Ca²⁺ from the cytosol into the ER lumen despite a much higher calcium concentration already existing inside the ER. ATP hydrolysis is required.
What is active transport?
Cholera toxin causes abnormally high intracellular levels of this molecule, leading to persistent activation of PKA.
What is cAMP?
A quality-control enzyme in the ER recognizes incompletely folded glycoproteins and reglucosylates them so they can re-enter the calnexin/calreticulin folding cycle.
What is glucosyltransferase in protein folding?
This amino acid sequence allows their retrieval from the Golgi back to ER
What is KDEL?
A chloride channel in intestinal epithelial cells becomes phosphorylated after cholera toxin exposure. Although it belongs to a transporter family normally associated with ATP-driven transport, it functions primarily as a gated chloride channel.
Kidney epithelial cells dramatically increase water permeability while excluding ions and most other solutes. The channel's non-regulated nature and selectivity depends on its narrow pore architecture.
What is aquaporin?
Upon activation by G protein, this enzyme cleaves PIP₂ into two signaling molecules that activate distinct downstream pathways.
What is Phospholipase C?
This major metabolic pathway occurs primarily in the smooth ER.
Without this targeting signal, acid hydrolases are secreted outside the cell rather than delivered to lysosomes.
What is Mannose-6-Phosphate?
This cellular system is responsible for the synthesis, processing, trafficking, and delivery of CFTR from the rough ER through the Golgi apparatus to the plasma membrane.
What is endomembrane pathway?
A membrane protein contains two ATP-binding domains and two transmembrane domains. ATP binding and hydrolysis drive conformational changes involved in substrate transport across membranes. CFTR is an example.
What is ABC Transporter?
A signaling molecule diffuses through the cytoplasm, binds receptors on the ER membrane, and triggers release of stored calcium.
What is IP3?
Following stimulation by IP₃, this major function of the ER directly supplies a key second messenger for intracellular signaling.
What is calcium storage?
A lysosome needs this ATP-driven transport system to maintain its acidity?
What is V-type pump?
Following calcium influx into the presynaptic terminal, synaptic vesicles fuse with the plasma membrane to release acetylcholine into the synaptic cleft.