?cl49614: cpPDZ_Deg_HtrA-like Superfamily
permuted PDZ domain of Deg/high-temperature requirement factor A (HtrA) family of housekeeping serine proteases and related domains PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of Deg/HtrA-type serine proteases that participate in folding and degradation of aberrant proteins, and in processing and maturation of native proteins. Typically, these proteases have an N-terminal serine protease domain and at least one C-terminal PDZ domain that recognizes substrates, and in some cases activates the protease function. An exception is yeast Nma11p which has two protease domains and four PDZ domains; its N-terminal half is comprised of a protease domain, followed by two PDZ domains, and its C-terminal half has a similar domain arrangement. HtrA-type proteases include the human HtrA1-4 and MBTPS2, tricorn protease, DegS, DegP and C-terminal processing peptidase, cyanobacterial serine proteases Hhoa, HhoB, and HtrA, and yeast Nma11p. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-termini of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains and as well as those with circular permutations and domain swapping of beta-strands. The canonical PDZ domain contains six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2); arranged as A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F. This Deg/HtrA family PDZ domain is a circularly permuted PDZ domain which places beta-strand A at the C-terminus. Another permutation exists in the PDZ superfamily which places both beta-strands A and B on the C-terminus.
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