InterPro: IPR000618 Insect cuticle protein

Insect cuticle is composed of proteins and chitin. The cuticular proteins seem to be specific to the type of cuticle (flexible or stiff) that occur at stages of the insect development. The proteins found in the flexible cuticle of larva and pupa of different insects share a conserved C-terminal section [1] such a region is also found in the soft endocuticle of adults insects [2] as well as in other cuticular proteins including in arachnids [3]. In addition, cuticular proteins share hydrophobic regions dominated by tetrapeptide repeats (A-A-P-A/V), which are presumed to be functionally important [2, 4]. Many insect cuticle proteins also include a 35-36 amino acid motif known as the R and R consensus. An extended form of this motif has been shown [5] to bind chitin. It has no sequence similiarity to the cysteine-containing chitin-binding domain of chitinases and some peritrophic membrane proteins, suggesting that arthropods have two distinct classes of chitin-binding proteins, those with the chitin-binding domains found in lectins, chitinases and peritrophic membranes (cysCBD), and those with the type of chitin-binding domains found in cuticular proteins (non-cysCBD) [5].

The cuticle protein signature has been found in locust cuticle proteins 7 (LM-7), 8 (LM-8), 19 (LM-19) and endocuticle structural glycoprotein ABD-4; Hyalophora cecropia (Cecropia moth) cuticle proteins 12 and 66; Drosophila melanogaster (Fruit fly) larval cuticles proteins I, II, III and IV (LCP1 to LCP4); drosophila pupal cuticle proteins PCP, EDG-78E and EDG-84E; Manduca sexta (Tobacco hawkmoth) cuticle protein LCP-14; Tenebrio molitor (Yellow mealworm) cuticle proteins ACP-20, A1A, A2B and A3A; and Araneus diadematus (Spider) cuticle proteins ACP 11.9, ACP 12.4, ACP 12.6, ACP 15.5 and ACP 15.7.