In addition, strong similarity in amino acid composition exists in the aligned areas of the two proteins (Fig. 4, lower panel),which consist almost entirely of Gly, Ala, Val, Gln and Glu. However, in contrast to the strong denaturation required for extraction of GAMP from the gastrolith chitin matrix, as reported by Ishii et al. in 1996 [31], GAMP-like is at least partly released from the C. quadricarinatus gastrolith matrix during calcium removal, without a requirement for any protein denaturing agent. Another difference between the two proteins lies in their lengths and properties. The GAMP sequence comprises two parts, each featuring
distinct amino acid content and a distinct sequence repeat; GAMP-like is significantly shorter and corresponds only to the first part of the GAMP sequence.