Dockerin type 1 <p>Gram-positive, thermophilic anaerobes such as <taxon tax_id="1515">Clostridium thermocellum</taxon> or <taxon tax_id="1521">Clostridium cellulolyticum</taxon> secretes a highly active and thermostable cellulase complex (cellulosome) responsible for the degradation of crystalline cellulose [<cite idref="PUB00000117"/>, <cite idref="PUB00001731"/>]. The cellulosome contains at least 30 polypeptides, the majority of the enzymes are endoglucanases (<db_xref db="EC" dbkey="3.2.1.4"/>), but there are also some xylanases (<db_xref db="EC" dbkey="3.2.1.8"/>), beta-glucosidases (<db_xref db="EC" dbkey="3.2.1.21"/>) and endo-beta-1,3-1,4-glucanases (<db_xref db="EC" dbkey="3.2.1.73"/>).</p><p>Complete sequence data for many of these enzymes has been obtained. A majority of these proteins contain a highly conserved type I dockerin domain of about 65 to 70 residues, which is generally (but not always) located in the C terminus. The dockerin domain is the binding partner of the cohesin domain (see <db_xref db="INTERPRO" dbkey="IPR002102"/>). The cohesin-dockerin interaction is the crucial interaction for complex formation in the cellulosome [<cite idref="PUB00005535"/>]. The dockerin domain contains a tandem repeat of two calcium-binding loop-helix motifs (distinct from EF-hand Ca-binding motifs). These motifs are about 24 amino acids in length. This entry represents these repeated Ca-binding motifs.</p>