N-Glycosylation – one pathway, two distinct selective constraints

Our group just published a new paper in BMC Systems Biology. The title isĀ Distribution of events of positive selection and population differentiation in a metabolic pathway: the case of asparagine N-glycosylation. It is already on the journal’s web page.

The pathway of N-Glycosylation can be ideally splitted into two separate parts, one upstream and one downstream of a process known as Calnexin/Calreticulin Cycle, in which an intermediate product of the pathway is involved. In theory, given their function, we can hypothesize that the two parts of the pathway are exposed to different selective constraint, and evolve at different paces among human populations.

The biology and function of the two parts of the pathway are explained in details in the article, but I will try to summarize them here. The upstream part of this pathway is required for this Calnexin/Calreticulin Cycle, a mechanism of folding quality control, so we can expect that all of his genes are conserved among populations. On the other hand, the downstream part of the pathway is involved in host-pathogen interactions, and can be expected to be more variable when comparing populations that adapted to different environments. In the article we have shown that in fact, signatures of population differentiation are more abundant in the downstream part of the pathway.

Unfortunately I don’t have much time to prepare a good presentation to illustrate the paper, but I have uploaded a short resume to slideshare. Have a look at it if you are interested:

You can also check this previous post, where I explained briefly that the main theme of work done in our lab is to study how selective constraints are distributed along the genes of a pathway.

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