Aspein
Aspein is an unusually acidic bivalve shell matrix protein, which may have important roles in calcium carbonate biomineralization.[1] The Aspein gene (aspein, Uniprot: Q76K52) encodes a sequence of 413 amino acids, including a high proportion of Asp (60.4%), Gly (16.0%), and Ser (13.2%), and the predicted isoelectric point is 1.78.[2] This is the most acidic of all the molluscan shell matrix proteins sequenced so far, or probably even of all known proteins on earth.[3] The main body of aspein is occupied by (Asp)2–10 sequences punctuated with Ser–Gly dipeptides. RT-PCR demonstrated that the transcript of aspein is expressed at the outer edge of the mantle, corresponding to the calcitic prismatic layer, but not at the inner part of the mantle, corresponding to the aragonitic nacreous layer. Aspein is likely responsible for directed formation of calcite in the shell of the pearl oyster Pinctada fucata.[4]
References
[edit]- ^ Tsukamoto, D; Sarashina, I; Endo, K (2004). "Structure and expression of an unusually acidic matrix protein of pearl oyster shells". Biochem Biophys Res Commun. 320 (4): 1175–80. doi:10.1016/j.bbrc.2004.06.072. PMID 15249213.
- ^ Kozlowski, LP (2016). "IPC - Isoelectric Point Calculator". Biology Direct. 11 (1): 55. doi:10.1186/s13062-016-0159-9. PMC 5075173. PMID 27769290.
- ^ Isowa, Y; Sarashina, I; Setiamarga, DHE; Endo, K (2012). "A comparative study of the shell matrix protein aspein in pterioid bivalves". J Mol Evol. 75 (1–2): 11–8. Bibcode:2012JMolE..75...11I. doi:10.1007/s00239-012-9514-3. PMID 22922907. S2CID 253774645.
- ^ Takeuchi, T; Sarashina, I; Iijima, M; Endo, K (2008). "In vitro regulation of CaCO(3) crystal polymorphism by the highly acidic molluscan shell protein aspein". FEBS Lett. 582 (5): 591–6. Bibcode:2008FEBSL.582..591T. doi:10.1016/j.febslet.2008.01.026. hdl:2241/100390. PMID 18242173.