Spiders coat their webs with sticky, adhesive substances that have been reported to facilitate prey capture. In orb weavers, the aggregate gland has been characterized as the structure that extrudes aqueous glue that coats the spiral capture threads. Chemical analysis of the aqueous glue solution has revealed high concentrations of organic compounds related to neurotransmitters, small peptides, free amino acids, low concentrations of inorganic salts and glycoproteins.55 Two cDNAs encoding glycoproteins have been reported in the literature and proposed to be major con­stituents of the glue droplets found on spiral capture threads; these products are named Aggregate Spider Glue 1 (ASG1) and Aggregate Spider Glue (ASG2).56 In cob-weaver spiders, data are emerging to suggest a different functional role for the aggregate gland (Fig. 1.1). In part, this could be somewhat anticipated and hypoth­esized because cob-weavers lack spiral capture silk. In cob-weavers the aggregate gland has been demonstrated to secrete two distinct proteins that are constituents of connection joints in three-dimensional webs, which are structures that glue scaffold­ing fibers together.57 These products, named Aggregate Gland Silk Factor 1 (AgSF1) and Aggregate Gland Silk Factor 2 (AgSF2), have markedly divergent protein ar­chitectures as well as are highly distinctive relative to protein sequences from tradi­tional fibroins. AgSF2, a 40-kDa nonglycosylated protein, has novel internal amino acid block repeats with the consensus sequence Asn-Val-Asn-Val-Asn (NVNVN), whereas AgSF1 contains pentameric Gln-Pro-Gly Ser-Gly (QPGSG) iterations that are similar to modular elements with mammalian elastin. AgSF1 has the potential to self-assemble into fibers and X-ray diffraction of synthetic threads reveals the pres­ence of noncrystalline domains that resemble classical rubber networks.57