Fig. 1. Two-dimensional electrophoretogram of proteins extracted from decalcified cuticle from the legs of Cancer pagurus. Approximately 250 μg protein was applied.

Fig. 2. Two-dimensional electrophoretogram of proteins extracted from arthrodial membranes of Cancer pagurus. Approximately 100 μg was applied.

Fig. 3. Fractionation of extracts from decalcified chelae (A) and of arthrodial membranes (B) from Cancer pagurus by gel-permeation on Sephacryl S200HR. The bars indicate the pooling of fractions.

Fig. 4. Reversed phase high-performance chromatography (RP-HPLC) fractionation of aliquot of protein pool collected from arthrodial membranes as indicated in Fig. 3B. The numbered peaks were collected for further characterization.

Fig. 5. Amino acid sequences for eleven proteins purified from extracts of decalcified solid cuticle of Cancer pagurus. The sequence of CpCP11.14 is included in Fig. 6. N-terminal pyroglutamate is indicated by pQ.

Fig. 6. Amino acid sequences for five proteins purified from arthrodial membranes of Cancer pagurus. The sequences are for comparison aligned to two proteins from Homarus americanus arthrodial membranes, and amino acid residues common for at least three of the five Cancer proteins are shaded. A gap (−) has been introduced into one of the sequences to optimize the alignment. The Rebers–Riddiford consensus sequence is shown above the alignments .N-terminal pyroglutamate is indicated by pQ, and a (+) above a residue indicates that it may carry an O-linked N-acetylhexosamine residue.

Fig. 7. Alignment of 18-residue motifs in Cancer exoskeletal proteins. The three conserved glycine residues are indicated by an asterisk (*). indicates a hydrophobic residue.

Fig. 8. Alignment of Cancer exoskeletal proteins, CpCP18.76 and CpCP14.99 to the Homarus protein HaCP20.2 .Amino acid identities are indicated by .

Fig. 9. Model proposed for the molecular arangement of chitin and proteins in pliant cuticles (left half) and in solid cuticles (right half). Chitin filaments are indicated as broad, cross-hatched bands; grey lines indicate protein regions bound to chitin (RR-1 and RR-2 sequences) and black, curled lines indicate protein chains in the interfilament space. Water molecules are indicated by ○.

Table 1. Molecular masses determined by mass spectrometry and calculated from the amino acid sequence of proteins purified from calcified exoskeleton and from arthrodial membranes of Cance pagurus^a