Presence of protein complex is prerequisite for aragonite crystallization in the nacreous layer.

We have isolated a protein complex from the nacreous layer of pearl beads and oyster shells. This complex was mainly composed of pearlin and pearl keratin. Addition of a minute amount of the complex to a calcium-carbonate-saturated solution containing Mg2+ induced aragonite crystallization.

Complementary DNA Cloning and Characterization of Pearlin, a New Class of Matrix Protein in the Nacreous Layer of Oyster Pearls.

Calcified shell layer is composed of two polymorphs of CaCO(3), aragonite or calcite, and an organic matrix. The organic matrix consists of EDTA-soluble and insoluble fractions. These fractions are thought to regulate the formation of the elaborate shell structure.

A comparative study of the immunity region of lambdoid phages including Shiga-toxin-converting phages: molecular basis for cross immunity.

Comparison of eight lambdoid phages, including three Shiga-toxin converting phages, has been carried out with respect to the immunity region, especially the recognition helices of their repressor and CRO proteins on the one hand, and operator sequences on the other. Some as yet unassigned components of the regulatory circuits have been inferred by computer search. The cross immunity phenomenon shown by phages VT2-Sa and lambda is explained on the basis of similarity in their sequences.

Sequence analysis of Stx2-converting phage VT2-Sa shows a great divergence in early regulation and replication regions.

In enterohemorrhagic Escherichia coli, Shiga toxin is produced by lysogenic prophages. We have isolated the prophage VT2-Sa that is responsible for production of Shiga toxin type 2 protein, and determined the complete nucleotide sequence of this phage DNA. The entire DNA sequence consisted of 60,942 bp, exhibiting marked similarity to the 933W phage genome.