Flashcards in B2.075 Protein Structure Function: Knowns and Unknowns Deck (23):
compare the exome and transcriptome portions of the genome
exome: all protein coding regions, 2% of genome, constant over lifetime
transcriptome: all transcribed RNA, changes with age and environment
how many differences exist between exomes of two unrelated people?
what are the classes of protein functions?
chemistry (enzymes), signaling, structure, transport, storage
what are the structural classes of proteins?
soluble/globular, fibrillar, integral membrane proteins, intrinsically disordered proteins
characterize globular/soluble proteins
hydrophobic inside, hydrophilic outside
2 or more polypeptides
contain alpha helices and beta sheets
1/3 of eukaryotic proteins
characterize fibrillar proteins
repeating globular subunits
long twisted fibers
what functions are associated with fibrillar proteins?
cytoskeleton and extracellular matrix
what are some well known fibrillar proteins?
repeating subunits: actin, tubulin
long polypeptides: collagen
characterize integral membrane proteins
hydrophobic on the outside, hydrophilic on inside
25-30% of human exome
what is one way to predict membrane spanning regions of amino acid sequences?
hydropathy plots: show hydrophobic stretches in sequence
what are functions commonly associated with integral membrane proteins?
characterize intrinsically disordered proteins
discovered by genome sequencing
30% of proteins in eukaryotes
long repetitive sequences
small sequence islands for binding w a range of partners
what functions are commonly associated with intrinsically disordered proteins?
scaffolding, transcription factors, membrane-less organelles
ex: dynein microtubule cargo transport
what is a post translational modification commonly associated with intrinsically disordered proteins?
can we predict structure of function of a protein from the sequence?
what are themes apparent from protein families?
conservation, motif, modularity
what are conserved residues?
impart common overall structure/function to a group of similar proteins
how do missense mutations affect conserved residues?
catastrophic...these residues are important to a group
what is a motif?
a conserved short sequence that is associated with a specific function (structure may or may not be known)
what are 2 examples of motifs?
zinc finger motif: needed for Zn2+ binding
walker A motif: needed for ATP binding
all common motifs have same sequence pattern and the rest of the protein can vary widely
what is protein modularity?
when you mix and match different structure/function classes on one polypeptide
how are contiguous domains on a protein connected?