Protein Components of Membranes & their Function

Question 1

3 Membrane Proteins

Answer 1

integral, lipid-anchored, & peripheral

Question 2

glycolipid

Answer 2

glycosylated lipid; only found on exterior leaflet of membrane

Question 3

Glycophorin A

Answer 3

transmembrane protein found on red blood cells; homomeric protein w/ coiled coil motif

Question 4

homomeric protein

Answer 4

2 of the same proteins combined to form quaternary structure

Question 5

Ion Channel Structure

Answer 5

tetrameric, hydrophobic aa on exterior, hydrophillic aa on interior

Question 6

Types of transmembrane proteins

Answer 6

ion channels & porins

Question 7

porin

Answer 7

channel for water & sugars; generally made of beta sheets

Question 8

3 lipid anchored proteins

Answer 8

GPI anchor, Acylation, & Prenylation

Question 9

GPI

Answer 9

glycosyl phospha tidyl inositol

Question 10

GPI-anchor

Answer 10

phosphatidylinositol contains two fatty acyl chains extended into bilayer, phosphoethanolamine links to C-terminus of protein, & sugar residues

Question 11

Acylation

Answer 11

cytosolic v-Src proteins; single fatty acyl chain attaches to N-terminal Glycine residue of polypeptide

Question 12

Prenylation

Answer 12

cytosolic Ras & Rab proteins; hydrocarbon chain attaches to Cysteine residues near C-terminus

Question 13

Acylation lipid anchors

Answer 13

myristate & palmitate

Question 14

Prenylation lipid anchors

Answer 14

farnesyl & geranylgeranyl

Question 15

glycosylation

Answer 15

addition of carbohydrate (sugar) chains to a protein; occurs on exoplasmic domain of most transmembrane & peripheral proteins

Question 16

carbohydrate group function

Answer 16

interact with extracellular matrix, growth factors, antibodies, etc

Question 17

Pleckstrin Homology (PH) Domain

Answer 17

most common lipid binding motif in peripheral membrane proteins; associates with phosphorylated inositols

Question 18

hypotonic

Answer 18

ion/solute concentration lower on outside/higher on inside; water moves inside

Question 19

hypertonic

Answer 19

ion/solute concentration higher on outside/lower on inside; water moves outside

Question 20

Common Functions of the Cell Membrane

Answer 20

junctions between cells (adherence & exrtacellular signaling) & cell surface receptors to bind signaling molecules