Figure 2.
(A) Amino acid composition of three common proteins in comparison to spider silk. (B) Model of the hierarchical structure of a MA silk protein. For example, Araneus diadematus Fibroin-3 (ADF3) has a highly repetitive core domain flanked by two nonrepetitive domains (aminoterminal domain: NRN; carboxyterminal domain: NRc). The aminoterminal domain also comprises a secretion signal sequence to allow protein export. (C) Amino acid motifs of silk proteins. The different amino acid motifs present in MA and Flag silk are correlated with their putative structure and their impact on the final properties of the thread. Although the function of the nonrepetitive parts is not fully understood, it is thought that these parts play a role in triggering the assembly of spider silks.