Figure 3

Lysine-270 and lysine-277 determine extracellular function of Hsp90α mutagenesis to identify the essential amino-acid residues for extracellular pro-motility activity of human Hsp90α. (a) Deletion mutagenesis narrowed the pro-motility activity of the 115-amino-acid F-5 fragment down to a 27-amino-acid peptide, F-8 fragment. (b) Comparison of F-8 from Hsp90α (F-8α) with the corresponding sequence of Hsp90β, F-8β, shows eight amino acids in F-8α (green) substituted with variant amino acids in F-8β (red). (c) Eight synthetic peptides with each of the eight amino acids in F-8α replaced with each of the corresponding amino-acid residues from F-8β (in red) were screened for their ability to rescue the motility defect of Hsp90α-knockout MDA-MB-231 cells, with F-8α and F-8β as positive and negative controls respectively. Quantitation of the cell motility is shown as MI (%). (d) K-270 and K-277 and their corresponding amino acids, G-262 and T-269, in Hsp90β were emphasized as focus of further studies.