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Petri Kursula lab
Flexible but not weak

Myelin protein disorder reviewed

Myelin, the insulative multilamellar sheath that enwraps axons, speeds up our nerve impulses by two orders of magnitude – a prerequisite for an efficient nervous system that we humans and other vertebrates enjoy. Myelin gains its structure and function from a high abundance of lipids and proteins, many of which are specific to this enigmatic biological system.

Single periaxin conformation
Disordered protein regions, such as the C-terminal extension of L-periaxin, exist as conformational ensembles of elongated chains, rather than well folded globular particles. Among many things, protein disorder enables multifunctionality – a common denominator of several myelin proteins.
Photo:
Arne Raasakka

The proteins of myelin might not be many in numbers, but they are enriched in quantity and highly specific to myelin. Several of these carry out multifunctional tasks in the structural integrity and formation of myelin, and intrinsic protein disorder carries an important role in achieving this.

Breakthroughs in the characterization of disordered myelin proteins, such as myelin basic protein, have been made in recent years. Regardless of this, however, several open questions remain in how these proteins contribute to the molecular foundation of demyelinating diseases, like the infamous autoimmune disease multiple sclerosis. Clear gaps also exist in the general understanding of the structure and function of several abundant proteins, such as the giant scaffolding protein periaxin.

We have published an up-to-date open access review on the structure-function relationships of disordered myelin proteins in health and disease. The vast amount of literature on several intrinsically disordered proteins has allowed us to review and speculate on their structure-function relationships. We also provide ideas on the disease etiology that arises from protein mutations and changes in the molecular composition on myelin – questions we aim to answer in the near future.

 

Citation:

Raasakka A. & Kursula P. (2020) Flexible Players within the Sheaths: The Intrinsically Disordered Proteins of Myelin in Health and Disease. Cells 9(2): 470. (open access)

Published in the Cells Special Issue on Structure and Function of Healthy and Diseased Myelin, edited by Petri.