Mastoparan activation of G proteins and NDPK.

[Steven McClue Genetics]

Dear martin,
	I don't know if this will be of interest, but I was working on the
 activation of heterotrimeric G-proteins by mastoparan and other short peptides
(usually chunks taken from various muscarinic receptors) before I came to
 Cambridge. I don't remember where I saw it, but I'm sure I've read that small MW G-
proteins can also be activated by such peptides. It really wouldn't surprise me
if this were the case, since the hetero- G-proteins can be activated by all 
kinds of things, not simply peptides.
	 As far as the results I got were concerned, it was possible to
 activate a purified mixture (some oxymoron there, I'm sure) of Gi/Go in
 reconstituted vesicles with peptide sequences as small as 7 amino-acids.
 We tried to find some logic (helicity, charge, hydrophobicity) to the results we got, but frankly couldn't. I'm very skeptical of the claims of
Nishimoto et. al. that they have found unifying patterns which allow them to
 design peptides to activate G-proteins (not least because they change the list of "activating sequences" from paper to paper!).
	If I can, I will try to find out where I saw the paper on activation
of small-MW G-proteins.

		Steve McClue
		sjm at mbfs.bio.cam.ac.uk