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. 2013 May 3;288(24):17844–17858. doi: 10.1074/jbc.M112.448639

FIGURE 3.

FIGURE 3.

A, auto-scaled attenuation percentages (53) of R3Aβ2m fingerprint HN-Hα TOCSY cross-peaks due to the presence of αB-crystallin. Data were obtained from integration of two-dimensional TOCSY spectra of 0.1 mm R3Aβ2m nonordinary samples, in the absence and presence of αB-crystallin at a molar ratio of 1:5 αB-crystallin/R3Aβ2m. Because of resolution limits, only 67 out of 94 expected HN-Hα connectivities could be integrated. The missing attenuation data were from Ile-1, Gln-2, Arg-12, Asn-17, Ser-20, Phe-22, Gly-29, Ser-33, Val-37, Leu-40, Arg-45, Lys-48, Glu-50, Ser-52, Leu-54, Ser-55, Ser-57, Lys-58, Trp-60, Ser-61, Leu-65, Thr-73, Glu-74, Tyr-78, His-84, Val-85, and Ser-88 cross-peaks, with no amide connectivity occurring for the prolyl residues at positions 5, 14, 32, 72, and 90 and the N-terminal methionine (M0). The attenuations exhibited a qualitatively identical pattern at a 1:15 molar ratio. However, greater attenuation (whose maximum was around 50%), which was more convenient for quantification, was observed at the higher αB-crystallin ratio. The location of the β-strand segments according to the NMR solution structure (19) is given at the bottom of the figure. The attenuation trend along the R3Aβ2m sequence exhibited a clear analogy with the results of the experiments performed at an equimolar concentration on an ordinary sample (Fig. 2A). B, schematic representation of β2m secondary structure showing A data, i.e. the attenuation levels of R3Aβ2m HN-Hα TOCSY connectivities due to αB-crystallin interaction observed in nonordinary samples. Class I MHC heavy chain (backbone schematic and space filling) is shown in transparency. The crystal structure coordinates of the complex were used (Protein Data Bank code 3HLA (10)). A three-color code was employed to report R3Aβ2m experimental attenuation, as indicated explicitly. The residue positions for which no attenuation data could be measured is colored gray. The small schematic aside shows the β-strand naming scheme of β2m. The drawing was prepared with PyMOL (DeLano Scientific LLC).