The silk specific antibodies identified these peptides as MaSp 1 and 2 derivates (Figure 7B).
Their sizes and reactivity to silk specific sera matched proteins extracted from the skin (Figure 3).
Proteins were either revealed by Ponceau S staining (Sigma-Aldrich) or reacted with biotinylated Concavalin A or silk specific antibodies.
The material reacted with silk specific sera (shown for S1Rx in Figure 7B; data not shown for S2Rx and S-pbs) identifying the material as major ampullate spidroins.
The proteins extracted from that layer showed sizes above 200 kDa similar to the known spidroins, but reacted with none of the silk specific sera.
The inner material is represented by the core and is made up by the known spidroins since it reacted with all silk specific sera (Figure 3).
The restriction of the two known MaSps to the core was proved by staining laser ablated fibres and fibre cross-sections with silk specific antibodies.
The material did not show any prominent protein bands in western blots nor was the material reactive to Concavalin A or any of our employed silk specific sera, which included reactivity against the repetitive parts of MaSp1 (S1Rx) and MaSp 2 (S2Rx) and native silk (S-pbs) [26] (Figure 3).
