2bv2

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spinqualitylabelsall models 2bv2, resolution 1.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

BETA GAMMA CRYSTALLIN FROM CIONA INTESTINALIS

Overview

A refracting lens is a key component of our image-forming camera eye;, however, its evolutionary origin is unknown because precursor structures, appear absent in nonvertebrates. The vertebrate betagamma-crystallin genes, encode abundant structural proteins critical for the function of the lens., We show that the urochordate Ciona intestinalis, which split from the, vertebrate lineage before the evolution of the lens, has a single gene, coding for a single domain monomeric betagamma-crystallin. The crystal, structure of Ciona betagamma-crystallin is very similar to that of a, vertebrate betagamma-crystallin domain, except for paired, occupied, calcium binding sites. The Ciona betagamma-crystallin is only expressed in, the palps and in the otolith, the pigmented sister cell of the, light-sensing ocellus. The Ciona betagamma-crystallin promoter region, targeted expression to the visual system, including lens, in transgenic, Xenopus tadpoles. We conclude that the vertebrate betagamma-crystallins, evolved from a single domain protein already expressed in the, neuroectoderm of the prevertebrate ancestor. The conservation of the, regulatory hierarchy controlling betagamma-crystallin expression between, organisms with and without a lens shows that the evolutionary origin of, the lens was based on co-option of pre-existing regulatory circuits, controlling the expression of a key structural gene in a primitive, light-sensing system.

About this Structure

2BV2 is a Single protein structure of sequence from Ciona intestinalis with CA, ACT and SO4 as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

Urochordate betagamma-crystallin and the evolutionary origin of the vertebrate eye lens., Shimeld SM, Purkiss AG, Dirks RP, Bateman OA, Slingsby C, Lubsen NH, Curr Biol. 2005 Sep 20;15(18):1684-9. PMID:16169492

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