Sandbox Reserved 1101: Difference between revisions

The process of the dragline fiber formation is the connection of soluble MaSp proteins into insoluble fibers. Indeed, MaSps are firstly secreted and stored in soluble form in the tail of the major ampullate gland which is located in the spider’s abdomen. On demand, they pass through the narrow duct where they experience mechanical and chemical forces that convert them into fibers. Actually, they deal with a pH dropping, an alteration of ion concentrations and oxidation conditions, which occur gradually along the duct. These changes promote the connection of MaSps extremities (i.e. homo-dimerisation of C- and N-terminal domains) to form fibers. Finally, through flow rate and mechanical forces experienced in the duct, the fibers will agglomerate to create the dragline silk.

The dragline fiber is mainly composed of proteins termed Major ampullate Spidroin 1 and Major ampullate Spidroin 2 (MaSp1 and MaSp2). MaSp1 is found in both the core and periphery of the fiber, while MaSp2 is only assembled in the core (Tokareva, et al., 2013). In Nephila clavipes, there are two distinct MaSp1 genes ; MaSp1A and MaSp1B (Gaines and Marcotte, 2008).