Fig. 5.

SSR and broadband UVB irradiation of HDF-derived microfibril isolations leads to changes in the proteolytic susceptibility of specific protein regions within fibrillin-1. LC-MS/MS-identified fibrillin-1 peptide sequences (PSMs: peptide prophet FDR ≤ 5%) were counted for each respective protein domain, normalised based on total spectrum count, averaged (N = 3) and subsequently heat mapped per group. Only domains containing an average of three peptides or more are shown. The PSM number corresponding to each broadband UVB- and SSR-irradiated fibrillin-1 domain were then subtracted from the counts of control and divided by the domain's primary sequence length to show regional fluctuations in proteolytic susceptibility (line graphs). Domains exhibiting significant differences in PSM numbers are also indicated (Bonferroni-corrected multiple comparisons tests taken from Fig. S2). Data-dependently quantified peptide sequences which were significantly different in relative abundance (taken from Fig. 3 B) are also mapped alongside their fold changes. UV-induced damage to fibrillin-1 is spread throughout the structure, although the N-terminal region (EGF 1) and EGFs 12, 22, 27, 33–34 and 43–45 appear the most affected. The pattern of changes seen throughout the fibrillin-1 structure is consistent in many regions, regardless of the UV irradiation source used (SSR or broadband UVB).