Linked Life Data

2738925

Source:http://linkedlifedata.com/resource/pubmed/id/2738925

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1989-8-8
pubmed:abstractText
gamma-Crystallins are a family of low molecular weight proteins found in high concentration in the densely packed regions of high refractive index in vertebrate lenses. Certain members have the characteristic property of a high critical temperature (tc) for phase separation. We report the three-dimensional structure determination of such a protein, bovine lens gamma IVa-crystallin, which has been refined to give an X-ray R-factor of 0.143. Its high tc contrasts with the low tc gamma II-crystallin, whose structure we have already published. The root mean square difference between the alpha-carbon atoms of these two proteins is 0.70 A and gamma IVa has an internal symmetry even higher than that of gamma II. The presence of a protein that exhibits the phenomenon of phase separation at body temperature renders the lens very susceptible to a transformation from transparent to an opaque state due to irregularities in the refractive index. Protein interactions of gamma IVa-crystallin have implications for the mechanism of cataract formation. Modes of self-association behaviour of gamma IVa-crystallin have been inferred from an analysis of the lattice interactions in the crystalline state, where the protein packing density is similar to that of the intact lens. It appears that the point mutation at position 103 from a serine residue in gamma II to a valine in gamma IVa gives rise to a lattice contact formed by two four-stranded beta-sheets in gamma IVa. A group-specific mutation at position 118 from leucine to phenylalanine induces subtle differences in core packing, leading to a reorganization around residue 103. However, the final phase separation determinant may be a complex combination of many side-chain functions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
207
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
217-35
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Packing interactions in the eye-lens. Structural analysis, internal symmetry and lattice interactions of bovine gamma IVa-crystallin.
pubmed:affiliation
Dept. of Crystallography, Birkbeck College, London, U.K.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't