Summary for clan SR

Summary Alignment Structure Literature
Clan type peptidaseS60.001 - lactoferrin (Homo sapiens), MEROPS Accession MER0020365 (peptidase unit: 20-357); PDB accession 1LCT
HistoryMEROPS 6.3 (23 June 2003)
DescriptionSerine nucleophile; catalytic residues in the order Lys, Ser in sequence
Contents of clanClan SR contains endopeptidases.
EvidenceThe 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 foldThe 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 familiesProteins 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).
Other databases SCOP53850


Family Family Type Peptidase Structure
S60 lactoferrin (Homo sapiens) Yes

Distribution of clan SR among Kingdoms of Organisms