Protein Function Flashcards
Classes of proteins:
- structural
- contractile
- defense
- transport
- signaling
- enzymatic
Examples of structural proteins:
- hair
- cell cytockeleton
Examples of contractile proteins:
- muscle
- motile cells
Examples of defense proteins:
- antibodies
- membrane proteins
Examples of transport proteins:
- hemoglobin
- membrane proteins
Example of signaling protein:
hormones
Enzymatic proteins regulate:
the speed of biochemical reaction
Fibrous protein differs from globulin proteins b/c…
they are usually elongated/fibrous in form
Examples of fibrous proteins:
- alpha keratins
- fibroin
- collagen
- elastin
Alpha keratins are the major proteins in…
- hair
- fingernails
- skin
Alpha keratins are the ______ filament protein
intermediate
Alpha keratins are predominately what shape?
alpha-helical
- twists together in left-handed coil
Every 4th residue of the alpha helix of alpha keratins is…
hydrophobic (makes one side hydrophobic)
- hydrophobic regions stick together
Fibroin:
fibers spun by silk worms and spiders
Fibroin have long regions of…
antiparallel beta sheet
Common sequence of fibroin:
- gly-ala or gly-ser
- allows for close packing
Collagen:
abundant matrix material in bone, tendons, and skin
Tropocollogen:
triplet helix made of left-handed helices w/ 3.3 residues per turn
Every 3rd residue of collage is a…
glycine (central residue)
- usually followed by proline/hydroyproline
Hydroxylation of proline requires…
vitamin C
Deficiency of vitamin C causes…
weak tendons due to inability to hydroxylation proline
What increases the toughness of collagen?
cross linking of lysine side chains (decreases elasticity)
Old bones and skin have more…
cross-links and are more brittle
Elastin is found in…
- blood vessels
- ligaments
Elastin is more elastic than…
collagen
Elastin is rich in:
- glycine
- alanine
- valine
Structure of elastin is…
mostly random coil
Elastin will cross-link via…
lysines
Actin:
G-actin monomers come together to form fibrous protein F-actin (has myosin binding sites)
Myosin:
- alpha helical tails and globular heads
- tails tend to aggregate
- heads tend to bind actin
Sarcomere:
basic repeating pattern of muscle myofibril
A band:
overlap of thick and thin filaments
I bands:
thin filaments only
