Fig. 1.

Predicted structure of B. amphitrite SIPC and similarity to the thioester region of Limulus sp. and other barnacles. (A) Predicted structure of the SIPC showing the putative disulfide bridge pattern deduced from the conservation of specific cysteine residues between SIPC and A2M. Thick lines indicate disulfide bridges that are conserved in the Limulus and human sequences. Light lines denote the disulfide bridge showing similarity only to Limulus. The 17-aa signal peptide is denoted by the black box. The potential N-linked glycosylation sites (Asn-Xxx-Ser/Thr and Asn-Xxx-Cys) are marked by black diamonds. (B) Amino acid sequence alignment of the thioester-like region from SIPC and A2M. Black and gray shading denotes identical and functionally similar amino acids, respectively. The horizontal lines indicate the amino acid sequences to which the forward and reverse PCR primers were designed. GenBank accession numbers are as follows: Limulus sp., T18544; B. amphitrite, AY423545 and AY781062; B. improvisus, AY781061; and M. rosa, AY781063.