Details

Autor(en) / Beteiligte

• Werten, Paul J.L.
• Lindner, Robyn A.
• Carver, John A.
• de Jong, Wilfried W.

Titel

Formation of βA3/βB2-crystallin mixed complexes: involvement of N- and C-terminal extensions

Ist Teil von

• Biochimica et biophysica acta, Protein structure and molecular enzymology, 1999-07, Vol.1432 (2), p.286-292

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

1999

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• The sequence extensions of the β-crystallin subunits have been suggested to play an important role in the oligomerization of these eye lens proteins. This, in turn, may contribute to maintaining lens transparency and proper light refraction. In homo-dimers of the βA3- and βB2-crystallin subunits, these extensions have been shown by 1H-NMR spectroscopy to be solvent-exposed and highly flexible. In this study, we show that βA3- and βB2-crystallins spontaneously form mixed βA3/βB2-crystallin complexes, which, from analytical ultracentrifugation experiments, are dimeric at low concentrations (<1 mg ml −1) and tetrameric at higher protein concentrations. 1H-NMR spectroscopy reveals that in the βA3/βB2-crystallin tetramer, the N-terminal extensions of βA3-crystallin remain water-exposed and flexible, whereas both N- and C-terminal extensions of βB2-crystallin lose their flexibility. We conclude that both extensions of βB2-crystallin are involved in protein–protein interactions in the βA3/βB2-crystallin hetero-tetramer. The extensions may stabilize and perhaps promote the formation of this mixed complex.