G-proteins

[Cornelius Krasel]

AJ. Collier (Adam.Collier at bristol.ac.uk) wrote:
> Is there anyone working on establishing whether a particular receptor 
> utilizes a heterotrimeric G-protein as part of its signal transduction 
> cascade.

> At the moment I am attempting to permeablize an epithelial cell 
> line with streptolysin-O, allowing the entry of GTP analogues into the 
> cell to see what effect this might have on signal transduction.

You could also try to measure effects or pertussis toxin, cholera toxin,
AlF4- or Mastoparan.

> Also, is there such a thing as a G-protein-linked receptor which DOESN'T 
> have 7 membrane spanning regions?

There have been claims that the IGFII/M6P receptor is G-protein coupled.
See e.g. the following paper and the references therein:

@article{takahashi:93,
	author	= {Katsutoshi Takahashi and Yoshitake Murayama and Takashi
		Okamoto and Takashi Yokota and Tsuneya Ikezu and Shuji
		Takahashi and Ugo Giambarella and Etsuro Ogata and Ikuo
		Nishimoto},
	title	= {Conversion of {G}-protein specificity of insulin-like
		growth factor {II} / mannose 6-phosphate receptor by
		exchanging of a short region with $\beta$-adrenergic
		receptor.},
	journal	= PNAS,
	volume	= 90,
	pages	= {11772--11776},
	year	= 1993
}

These claims are refuted in a very recent JBC paper, however (the paper
has appeared either in No. 51 or 52 of JBC, but these haven't arrived
in our library yet).

--Cornelius.

--
/* Cornelius Krasel, Abt. Lohse, Genzentrum, D-82152 Martinsried, Germany  */
/* email: krasel at alf.biochem.mpg.de                 fax: +49 89 8578 3795  */
/* "Science is the game you play with God to find out what His rules are." */