The minor ampullate (MI) gland is morphologically similar to the MA gland, but it is smaller in size (Fig. 1.1). MI silks are often present with MA silks, which form four fibers in dragline silks; two large diameter MA silk fibers and two smaller MI silk threads (Fig. 1.2). MI silk has been proposed to consist of two spidroin family members, Minor Ampullate Spidroin 1 (MiSp1) and Minor Ampullate Spidroin 2 (MiSp2).44 Recently, the complete cDNA sequence for MiSp from the orb-weaver spider, Araneus ventricosus, was deposited in the GenBank database.45 Analysis of the MiSp1 cDNA sequence predicts a 1766 amino acid residue protein organized into conserved nonrepetitive N — and C-terminal domains and internal repetitive re­gions composed of four submodules that are iterated in a nonregular manner. Simi­lar to MA fibroins, the predicted sequence is dominated by poly A and GGX, as well as Gly Gly Gly X (GGGX), Gly X (GX) motifs and spacer segments.