Modular proteins Flashcards
definition of a domain
a folded structural unit; the sequence need not be contiguous e.g. MHC II
definition of a module
a domain with a contiguous sequence, repeatedly used in diverse proteins eg. F3
definition of a repeat
a unit that does not fold in isolation; several copies are needed eg. Leu-rich repeat
how many domains is the e.coli proteome made up from
about 400 domains
how many domains does the eukaryote genome contain
around 600-700 domains
what are the two levels of protein evolution
- variation of individual amino acids
- larger-scale variation involves trying out various domain combinations
name 5 biological implications of protein domains?
- many surfaces using the same scaffold
- presentation of binding sites
- assembly
- regulation
- poly-valency
What does presentation mean in terms of domains?
the variable position of binding surface on constant scaffold
briefly describe EGF’s structure
- about 40 residues
- three disulphide bonds
- two-stranded beta-sheet followed by a loop to a C-terminal short two-stranded sheet
- subdomains between the conserved cysteines vary in length
what binds to EGF?
calcium
what is the main block for fibrillin?
tandem cbEGF (calcium bound EGF)
describe calcium bound EGF (cbEGF)
- three disulphide bonds
- two-stranded beta sheet followed by a loop to a C-terminal short two stranded sheet
- often as a tandem repeat
- main building block for fibrillin
what does fibrillin do?
forms microfibrils that are part of the ECM
What syndrome has over 500 mutations?
marfan syndrome
what do domain junctions have the potential to be ?
hinge regions
