TABLE 1.

Dimensions of fibrillar species observed by AFM for four different proteins

Protein	Protofilaments (nm)*	Protofibrils/fibrils (nm)†	Amino acid content (monomer dimensions)‡
α–Synuclein	3.8 ± 0.6	6.5 ± 0.6 (100–150 nm) 9.8 ± 1.2	140 aa (natively unfolded, dimensions not available)
Insulin	1.2 ± 0.3	1.9 ± 0.3 3.0 ± 0.4, 4.8 ± 0.4	51 aa (3.1 × 3.3 × 2.2 nm)
B1 domain of protein G	1.9 ± 0.9	3.9 ± 0.3, 5.2 ± 0.3	58 aa (3.5 × 2.2 × 2.0 nm)
Ig variable-domain SMA§	2.5 ± 0.4	4.5 ± 0.5, 5.9 ± 0.6, 8.0 ± 1.0 (60 nm, 110 nm)	114 aa (4.0 × 2.5 × 1.4 nm)

^*Protofilament diameters as inferred from protofilament average-height measurements plotted as histograms, and the smallest peak height from the histograms in Figs. 2, 5, and 7 is estimated as protofilament diameter.

^†Diameter measurements for higher-order species protofibrils/fibrils, also derived from the histogram peaks. In parenthesis are the periodicities of some species, where available.

^‡The amino acid count for each of the proteins and the dimensions of the natively folded conformation, as measured by x-ray crystallography or NMR techniques.

^§SMA, initials of the patient whose sequence was used to clone the gene coding for variable domain of Ig light chain.