MEMBRANE TRANSPORT

Question 1

GLUT1

Answer 1

Mode of transport: facilitated diffusion
Allows movement of: Glucose
Found in: RBC’s, blood-brain barrier, kidney
Notes: High affinity transporter (small amounts allows movement); remains at constant rate at normal & lower blood glucose concentrations

Question 2

GLUT2

Answer 2

Mode of Transport: Facilitated
Allows movement of: Glucose
Found in: Intestinal mucosal cells, liver, pancreatic beta cells, renal tubular cells
Notes: Low affinity transporter (large amounts required for movement); important in re-uptake of glucose

Question 3

GLUT3

Answer 3

Mode of Transport: Facilitated
Allows movement of: Glucose
Found in: Brain (neurons)
Notes: High affinity transporter (small amounts allow movement); constant rate at normal and lower blood glucose concentrations

Question 4

GLUT4

Answer 4

Mode of Transport: Facilitated
Allows movement of: Glucose
Found in: Fat cells, skeletal muscle, heart
Notes: High affinity transporter (small amounts allows movement); Insulin dependent

Question 5

GLUT5

Answer 5

Mode of Transport: Facilitated
Allows movement of: Fructose & Glucose
Found in: Luminal side of intestinal membrane, seminal vesicles
Notes: Low affinity transporter (large amounts required for movement); prefers fructose over glucose

Question 6

SGLT1

Answer 6

Mode of Transport: Secondary active
Allows movement of: Na+ & Glucose/Galactose
Found in: Intestinal mucosal cells
Notes: Symporter; ATP dependent

Question 7

SGLT2

Answer 7

Mode of Transport: Secondary active
Allows movement of: Na+ & Glucose
Found in: Kidneys
Notes: Re-uptake of sodium and glucose in the kidneys; SGLT2 inhibitors used in treatment of diabetes (prevents re-uptake of glucose back into blood); ATP dependent

Question 8

ABC (ATP Binding Cassette)

Answer 8

Mode of Transport: Active
Allows movement of: Lipids or lipid-related compounds (biles, salts, cholesterol, bilirubin)
Found in: All cells
Notes: In eukaryotes, allows active transport from cytosol to extracellular space - requires ATP hydrolysis

Question 9

CFTR (Special type of ABC transporter)

Answer 9

Mode of Transport: Passive
Allows movement of: Cl-
Found in: All cells
Notes: A gated pore for Chloride ions, once open Cl- will flow down gradient
Ex. Cystic Fibrosis - CFTR deficiency: abnormal viscous mucus buildup

Question 10

Na+/K+ ATPase

Answer 10

Mode of Transport: Primary Active
Allows movement of: Na+/K+
Found in: All cells
Notes: Transports 2 K+ ions in & 3 Na+ ions out; ATP dependent (against gradient)