9CBV

MicroED structure of the human MP20 protein

Summary for 9CBV

• Entry DOI: 10.2210/pdb9cbv/pdb
• EMDB information: 45428
• Descriptor: Lens fiber membrane intrinsic protein (1 entity in total)
• Functional Keywords: lens, cataract, microed, tetraspanin, cell adhesion
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 25160.51

Authors

Nicolas, W.J.,Shiriaeva, A.,Martynowycz, M.W.,Grey, A.C.,Ruma, Y.,Donaldson, P.J.,Gonen, T. (deposition date: 2024-06-20, release date: 2025-05-21)

Primary citation

Nicolas, W.J.,Shiriaeva, A.,Martynowycz, M.W.,Grey, A.C.,Ruma, Y.N.,Donaldson, P.J.,Gonen, T.
Structure of the lens MP20 mediated adhesive junction.
Nat Commun, 16:2977-2977, 2025

PubMed Abstract: Human lens fiber membrane intrinsic protein MP20 is the second most abundant membrane protein of the human eye lens. Despite decades of effort its structure and function remained elusive. Here, we determined the MicroED structure of full-length human MP20 in lipidic-cubic phase to a resolution of 3.5 Å. MP20 forms tetramers each of which contain 4 transmembrane α-helices that are packed against one another forming a helical bundle. We find that each MP20 tetramer formed adhesive interactions with an opposing tetramer in a head-to-head fashion. Investigation of MP20 localization in human lenses indicate that in young fiber cells MP20 is initially localized to the cytoplasm in differentiating fiber cells but upon fiber cell maturation is inserted into the plasma membrane, correlating with the restriction of the diffusion of extracellular tracers into the lens. Together these results suggest that MP20 forms lens thin junctions in vivo, confirming its role as a structural protein in the human eye lens essential for its optical transparency.

PubMed: 40140346
DOI: 10.1038/s41467-025-57903-6

Experimental method

ELECTRON CRYSTALLOGRAPHY (3.5 Å)