Proteins 2 Flashcards
Give some examples of modified types of proteins?
Glycoproteins
Lipoproteins
Metalloproteins
What are glycoproteins?
Compound composed of protein and carbohydrates
How to glycoproteins occur?
From a post-translational modificaiton where a sugar molecule binds via an amino acid in the protein
What are some of the roles of glycoproteins?
Protein stabalisation
Affect solubility
Protein orientation
Signalling
Cell recognition
What is the process of forming a glycoprotein called?
Glycosylation
Where does glycosylation occur?
The endoplasmic reticulum and the golgi apparatus
What are some examples of glycoproteins?
Immunoglobulins
Blood group determinants
What are lipoproteins?
Proteins and lipids bonded together
What is the function of lipid proteins?
Transport insoluble fat and cholesterol in the blood
What are examples of lipoproteins?
High density lipoproteins (HDL)
Low density lipoproteins (LDL)
What are metalloproteins?
Protein molecules with a bound metal ion
What are some examples of metalloproteins?
Enzymes
Storage
Signilling
Transport
What are the three structures of proteins?
Globular (varied function)
Fibrous (structural function)
Membranous (associated with cell or orangelle membrane)
What are some examples of globular proteins?
Enzymes
Messengers (hormones)
Transporters
Stack of amino acids
Structural function such as actin or tubulin
What are some examples of fibrous proteins?
Bone matrices
Muscle fibres
Tendons
Connective tissue
What are some examples of membranous proteins?
Relay signal
Membrane transporter
Membrane enzyme
Cell adhesion molecule
What is a specific example of a globular protein?
Haemoglobin
How does haemoglobin operate?
Carries O2
Haem group at the centre of each polypeptide chain binds to a moleucle of O2
Composed of 4 units, so you can carry 4 molecules of O2
What does the binding of O2 do to the shape of haemoglobin?
Changes its conformaiton which allows for more O2 to bind easier
What is cooperative binding?
When a molecules binds to a protein and makes it easier for other molecules to bind
What is a specific example of a fibrous protein?
Collagen
What is the structure of collagen?
Three polypeptide chains coil around each other
Held together by hydrogen bonds
Composed of repeated units (glycine - x - proline)n
where x = alanine, hydroxyproline or lysine)
What happens when collagen interacts with each other?
They form fibriles and increase strength
What kind of receptors are present in all cells and what do they allow?
LDL receptors
They allow the internalisation of LDL which is then broken down in lysosomes
What are 5 possible classes of LDL receptor mutations?
- Class 1 - no receptor produced
- Class 2 - receptor never reach the cell surface
- Class 3 - receptor can’t bind to LDL
- Class 4 - receptors don’t internalise on binding
- Class 5 - receptors don’t release LDL
