Dragline silk is composed of two proteins, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2) [1]. MaSp1 contains five alpha-helices [2]. Only the C-terminus of the proteins are shown.

1: Analysis of the conserved N-terminal domains in major ampullate spider silk proteins. Motriuk-Smith D, Smith A, Hayashi CY, Lewis RV; Biomacromolecules. 2005;6:3152-3159. PMID:16283740

2: N-terminal nonrepetitive domain common to dragline, flagelliform, and cylindriform spider silk proteins. Rising A, Hjalm G, Engstrom W, Johansson J; Biomacromolecules. 2006;7:3120-3124. PMID:17096540