Globular domains

Centrins are calmodulin-like proteins that have an important function in the organization and duplication of microtubules. Like CaM, centrin is also comprized of two structurally independent globular domains connected by a flexible tether, and each domain is... 

Intrastrand bonding via disulphide links cause the molecule to fold into globular domains and it is these that direct the biological activity of the molecule. 

No ligand EphB2 receptor N-terminal globular domain - —... 

Calmodulin (CaM) undergoes drastic conformational change when it binds Ca2+ and amphiphilic peptides such as mas to po ran and endorphin, which results in the modulation of many important biochemical reactions. The N-terminal and C-terminal of rigid structured globular domains are bridged with a long flexible peptide of a-helical structure. Each domain binds two Ca2+ ions to its hydrophobic sites. 

Fig. 6. Terminal capping and lateral bulging of globular domains in the //-solenoid of the hemoglobin protease from E. coli (Otto et al., 2005). The //-solenoid domains are shown in blue and the remaining regions in dark yellow. (A) Ribbon diagram of the 3D structure and (B) linear map of the domain distribution within the amino acid sequence.

C. Role of Globular Domains in the Folding of Triple /.-Stranded... 

The T4 short tail fiber triple /l-helix is connected to a more globular head domain via residues 333-341, which form a very short a-helical triple coiled-coil. Residues 342-396, together with the C-terminal /1-strand composed of amino acids 518-527 (the collar ), are the only part of the structure in which the monomer has a recognizable fold. It may therefore be the first part of the protein to fold, followed by a zipping-up of the N-terminal domain and the top domain. The small, globular, domain contains six /1-strands and one a-helix and has some structural homology to gpl 1, also of bacteriophage T4. Three of the /1-strands and the a-helix formed by residues... 

Fig. 3. Structures of prion protein globular domains. (A) Crystal structure of the C-terminal domain dimer of Ure2p (pdb file 1HQO). (B) NMR structure of the C-terminal domain monomer of PrP (pdb file 1E1G).

Filaments of full-length Ure2p are wider than prion domain filaments and they are not smooth-sided (Fig. 5) rather they have a backbone that closely resembles prion domain filaments in width, surrounded by globular domains—presumably, the G-terminal functional domains. This interpretation is supported by the results of protease digestion experiments that trim filaments of full-length Ure2p down to 4-nm core fibrils that closely resemble prion domain filaments assembled de novo (Fig. 5 Baxa et al, 2003). 

Ure2p filaments are not smooth-sided and their width, at 20 nm, exceeds the range normally associated with amyloid filaments. However, these apparent discrepancies are reconciled by the consideration that it is only the filament backbone of polymerized prion domains that is amyloid (Section III.C and III.D). Its width of 4 nm or so is in the typical amyloid range and these filaments are smooth-sided (Fig. 5). The greater width of Ure2p filaments and the fact that they are not smooth-sided is explained by the amyloid backbone being decorated by still folded globular domains. 

Fay et al. (2005) have proposed a completely different model for Ure2p fibril structure. Their model is based on data which suggest that Ure2p fibrils do not have a cross-/ structure (Bousset et al., 2003) and that the C-terminal globular domain is tightly involved in the fibrillar scaffold (Bousset et al.,... 

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