Fig. 1.

Unusual proline-rich proteins (MaSp4a and MaSp4b) among Caerostris darwini major ampullate Spidroin (MaSp) proteins. a Schematic of spider silk proteins (spidroins) composed of tandem-repeated amino acid sequences (ensemble repeats) flanked by non-repetitive amino (N)- and carboxy (C-) terminal domains. b Caerostris darwini MaSp proteins with each box presenting consensus repeat and repeat numbers determined from the longest sequence of each type (full sequences in Supplementary Data 10); poly-alanine (A_n) motifs in red, GPGX (X = G, S, A, or Q) in blue, and GPGPQ motifs in purple. c MaSp4a protein aligning consecutive ensemble repeats with C-terminal domain italicized, highlighting GPGPQ and GPGX as above