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Figure 5 | Proteome Science

Figure 5

From: In-depth proteomic analysis of a mollusc shell: acid-soluble and acid-insoluble matrix of the limpet Lottia gigantea

Figure 5

The amino acid sequence of the Gly/Asn-rich protein in Lotgi1|239447. This was one of the most abundant proteins in the acid-soluble matrix. The sequence contained a Gly/Asn-rich domain (aa41–105; shaded yellow) consisting of 55% Gly and 28% Asn. This is followed by a cysteine-containing domain (cysteines shaded green) that can be presumed to have a more rigid structure stabilized by disulfide bonds. The Gly/Asn-rich domain did not yield a peptide because of the lack of tryptic cleavage sites. However, it is framed by MS/MS-sequenced peptides. A very similar G/N-rich sequence region was found in the otherwise unrelated shell protein GAAP_HALAI, identified in Haliotis asinina[6] and in nacrein_like proteins [7, 46]. Sequences covered by MS/MS are in red, the peptide giving rise to the spectrum is in bold italics and underlined. The doubly charged peptide with m/z 994.4501 and a deviation from the calculated value of 0.1 ppm had a PEP of 4.7E-13. Very typically, the most intense fragments, y8 and y10, were produced by preferential fragmentation N-terminal to Pro and in the +1 position of Pro.

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