Summary for clan SR
| Clan type peptidase | S60.001 - lactoferrin (Homo sapiens), MEROPS Accession MER0020365 (peptidase unit: 20-357); PDB accession 1LCT |
| History | MEROPS 6.3 (23 June 2003) |
| Description | Serine nucleophile; catalytic residues in the order Lys, Ser in sequence |
| Contents of clan | Clan SR contains endopeptidases. |
| Evidence | The structure of lactoferrin (S60.001) is unlike that of other peptidases (see Protein fold). |
| Catalytic mechanism | (See family S60.) |
| Peptidase activity | (See family S60.) |
| Protein fold | The tertiary structure has been determined for lactoferrin (S60.001: Anderson et al., 1987). Lactoferrin shows a fourfold duplication. Each single repeat contains a beta sheet (with strands in the order 21354, and strand 5 antiparallel to the rest) sandwiched between two layers of helices. There are two peptidase units and each consists of two structural repeats. Each peptidase unit has a single structural iron ion atom at the interface of the repeats. Only the N-terminal peptidase unit has an active site, at the surface of the N-terminal structural repeat. |
| Homologous non-peptidase families | Proteins with related folds include transferrin and ovotransferrin. A similar, unrelated fold is seen for several periplasmic binding proteins from bacteria, including oligopeptide-binding protein, dipeptide-binding protein and histidine-binding protein and ferric-binding protein, and some eukaryote receptors such as glutamate receptor ligand binding core and subunit 1 of the N-methyl-D-aspartate receptor (see SCOP sunid 53850). |
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Other databases
| SCOP | 53850 |
Families
| S60 |
lactoferrin (Homo sapiens) |
Yes |
Distribution of clan SR among Kingdoms of Organisms
