All types of transporters Flashcards
(29 cards)
What is the function of the Sodium-Potassium ATPase (Na+/K+ ATPase), and where is it found?
It actively transports sodium (Na+) out of the cell and potassium (K+) into the cell against their concentration gradients.
Found in: All cells, particularly abundant in kidney tubule cells (proximal convoluted tubule, distal convoluted tubule, and collecting ducts).
What is the function of the Sodium-Glucose Transporter (SGLT1 and SGLT2), and where is it found?
It co-transports sodium (Na+) and glucose into cells.
Found in: SGLT1 is primarily in the small intestine and proximal tubule of the kidney. SGLT2 is mostly in the proximal convoluted tubule of the kidney.
What is the function of the Na+/H+ Exchanger 3 (NHE3), and where is it found?
It exchanges sodium (Na+) for hydrogen ions (H+) to regulate intracellular pH.
Found in: Proximal convoluted tubule (PCT) of the kidneys, epithelial cells of the intestine.
What is the function of the Proton Pump (H+/K+ ATPase), and where is it found?
It actively pumps hydrogen ions (H+) into the stomach lumen in exchange for potassium (K+).
Found in: Parietal cells of the stomach lining.
What is the function of the Na+/Cl− Cotransporter (NCC), and where is it found?
It co-transports sodium (Na+) and chloride (Cl−) ions across membranes.
Found in: Distal convoluted tubule (DCT) of the kidney.
What is the function of the K+/Cl− Cotransporter 2 (KCC2), and where is it found?
It transports potassium (K+) and chloride (Cl−) ions out of the cell.
Found in: Various tissues, particularly in the thick ascending limb (TAL) of the kidney.
What is the function of Aquaporins (AQP), and where is it found?
They facilitate the passive transport of water across cell membranes.
Found in: Various tissues, including the kidneys (AQP1 in the proximal tubule and AQP2 in the collecting ducts).
What is the function of the Chloride-Bicarbonate Exchanger 1 (AE1), and where is it found?
It exchanges chloride (Cl−) for bicarbonate (HCO3−) to regulate pH.
Found in: Distal convoluted tubule and collecting duct in the kidney, red blood cells, and some epithelial cells.
What is the function of Organic Anion Transporter 1 and 3 (OAT1 and OAT3), and where is it found?
They transport organic anions (e.g., drugs, metabolites) into or out of cells.
Found in: Proximal convoluted tubule (PCT) of the kidney, hepatocytes, and the brain.
What is the function of Organic Cation Transporter 1 and 2 (OCT1 and OCT2), and where is it found?
They transport organic cations (e.g., drugs, toxins) into cells.
Found in: Proximal convoluted tubule (PCT) of the kidney, liver, and neurons.
What is the function of the Calcium-Sodium Exchanger (NCX), and where is it found?
Found basolaterally
It exchanges sodium (Na+) for calcium (Ca2+), helping to regulate intracellular calcium levels.
Found in: Various tissues, including the kidneys, heart, and neurons.
What is the function of Symporters and Antiporters in the Kidney (e.g., NKCC2, NCC), and where are they found?
NKCC2 (Sodium-Potassium-Chloride Cotransporter 2): This transporter moves sodium (Na+), potassium (K+), and chloride (Cl−) into the cell in the thick ascending limb (TAL) of the nephron. It plays a critical role in maintaining the kidney’s ability to concentrate urine by driving the reabsorption of these ions and creating an osmotic gradient.
NCC (Sodium-Chloride Cotransporter): Found in the distal convoluted tubule (DCT), it co-transports sodium (Na+) and chloride (Cl−) from the tubular fluid into the cell. It helps to further fine-tune the balance of electrolytes, especially during sodium retention.
Both transporters contribute to the kidneys’ ability to regulate electrolyte balance and urine composition, with NKCC2 playing a key role in sodium, chloride, and water reabsorption and NCC in fine-tuning sodium reabsorption.
Found in:
NKCC2: Thick ascending limb (TAL) of the loop of Henle.
NCC: Distal convoluted tubule (DCT) of the nephron.
What is the function of GLUT (Glucose Transporters) in the kidney, and where are they found?
GLUT1: Found primarily in the proximal convoluted tubule (PCT) of the nephron, where it facilitates the reabsorption of glucose from the tubular fluid back into the blood.
GLUT2: Present in the proximal straight tubule (PST) and the basolateral membrane of the PCT, this transporter helps in the efficient movement of glucose from the cells into the blood.
GLUT4: Although not primarily found in the kidney, it is present in certain other tissues and can be involved in glucose regulation under insulin stimulation. (insulin-sensitive one)
GLUT1: Proximal convoluted tubule (PCT)
GLUT2: Basolateral membrane of the PCT
What is the function of ENaC (Epithelial Sodium Channel) in the kidney, and where is it found?
ENaC is responsible for the reabsorption of sodium from the urine into the epithelial cells of the nephron, particularly in the distal convoluted tubule (DCT) and collecting ducts. This plays a crucial role in regulating sodium balance, blood volume, and blood pressure.
It is sensitive to aldosterone, which increases the number of ENaC channels, thereby enhancing sodium reabsorption.
Found in:
- Distal convoluted tubule (DCT)
- Collecting ducts
What is the function of TRPM6 in the kidney, and where is it found?
TRPM6 is a magnesium transporter that facilitates the reabsorption of magnesium in the kidney, specifically in the distal convoluted tubule (DCT).
TRPM6 is an essential protein for magnesium homeostasis in the body, as it allows the kidneys to retain magnesium and prevent its excessive excretion in urine.
Found in:
Distal convoluted tubule (DCT)
What is the function of ROMK in the kidney, and where is it found?
ROMK is a potassium channel that is responsible for secreting potassium from the cells of the nephron into the urine, particularly in the distal convoluted tubule (DCT) and collecting ducts.
It plays a major role in maintaining potassium balance and helps to regulate electrolyte homeostasis by ensuring potassium is properly excreted in the urine.
ROMK2 can transport ammonia ions into the cell
Found in:
- Distal convoluted tubule (DCT)
- Collecting ducts
What receptor does ADH bind to
ADH binds to the V2 receptor, which is found in the distal convoluted tubule and collecting ducts of the kidney.
What receptor does Angiotensin II bind to?
Angiotensin II binds to the AT1 receptor, which is found in the kidney, blood vessels, and adrenal glands.
What receptor does Aldosterone bind to?
Aldosterone binds to the Mineralocorticoid Receptor (MR), which is found in the distal convoluted tubule and collecting ducts of the kidney.
Sodium absorption in late PCT transporters involved
Apical transporters:
- NHE-3 (Na/H exchanger)
Basolateral exchanger:
- NHE-1
Sodium absorption in ascending loop transporters involved
Na+/K+/2Cl- co-transporter (NKCC2)
Sodium absorption in DCT and collecting duct (fine tuning)
Aldosterone increases transcription and insertion of ENaC which allows for Na absorption
Water entering DCT and collecting duct
Aquaporin-2 (AQP2) (ADH causes the insertion of these channels)
Water leaving DCT and collecting duct
Aquaporin 3 and 4 (AQP3 and 4)
