Figure 4.

(A) Amino acid sequence of silicatein α deduced from cDNA. The putative signal peptidase cleavage site is marked with an arrow; the observed boundary between the propeptide and mature peptide is shown by an arrowhead. Amino acid sequences obtained from peptide sequencing are underlined as follows: solid line, N-terminal sequence; long-dashed, endoproteinase Asp-N fragments; short dashed, endoproteinase Glu-C fragment; and dotted, endoproteinase Lys-C fragment. (B) Northern hybridization analysis of silicatein α transcript. Total RNA prepared from regenerating sponge tissue was subjected to Northern blot analysis with digoxigenin-labeled RNA probe as described in the text.