The flagelliform gland appears to have different biological functions in orb-weavers relative to cob-weavers. Orb-weavers spin flagelliform silk (Flag silk) into two­dimensional webs and these fibers are known as spiral capture silk. The main pro­tein constituent of Flag silk has been shown to have several distinctive features, including iterations of GPGGX motifs, GGX, highly conserved spacer regions with charged and hydrophilic residues, and a nonrepetitive C-terminal domain that is di­vergent from the other spidroin family members.46 Flag silk represents the most ex­tensible silk type produced by orb weaver spiders, being able to stretch 200% of its own length before fiber failure. The GPGGX module, which is also present within the protein sequence of MaSp2, is responsible for the elasticity and extensibility of flagelliform silk; iterations of these motifs have been hypothesized to form type II beta-turns that assemble into beta-turn nano-spring structures.47 Recently, ana­lyzes of flagelliform silk using Raman spectroscopy from three different orb-weaver species have revealed correlations between increased tensile strength and higher amounts of beta-sheet structure, which can be attributed to greater number of spacer regions.48 This is consistent with the observation that recombinant fibers spun with only spacer regions are stronger relative to synthetic silks spun from recombinant proteins that contain spacer regions, GGX and GPGGX modules.49 In cob-weavers, which spin three-dimensional webs that lack spiral capture, the flagelliform gland has not been reported to extrude fibroins or fibroin-like proteins (Fig. 1.1); however, two small peptides dubbed Spider Coating Peptide 1 (SCP-1) and Spider Coating Peptide 2 (SCP-2) have been detected.50 MS/MS studies have demonstrated that the SCPs are present on egg cases, scaffolding threads, gumfooted lines and attachment discs. Recombinant expressed SCP-1 has been shown to bind to a nickel resin, sug­gesting it has intrinsic metal binding activity and potential antimicrobial effects. Growth studies with the gram-negative bacterium E. coli support this assertion, as addition of either SCP-1 or SCP-2 to rapidly dividing bacterial cells is able to slow cellular division (unpublished data).