Family I24

Family

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Summary for family I24

Name	Inhibitor family I24 (pinA family)
Family type peptidase	I24.001 - pinA Lon peptidase inhibitor (phage T4) (Enterobacteria phage T4), MEROPS Accession MER0018324 (inhibitor unit: 1-161)
Content of family	Family I24 contains inhibitors of serine endopeptidases from family S16.
History	Identifier created: MEROPS 6.1 (10 January 2003) An inhibitor of the Escherichia coli ATP-dependent endopeptidase La (S16.001) was first described from the bacteriophage T4 in 1988; the inhibitor is the product of gene 49.1 (or pinA) in the phage genome (Skorupski et al., 1988).
Peptidases inhibited	PinA inhibits endopeptidase La from family S16 (Hilliard et al., 1998).
Mechanism of inhibition	PinA forms a complex with endopeptidase La which is reversible. PinA exists as a homodimer and a homotrimer, and gel filtration studies have shown that an endopeptidase La homotetramer associates with a pinA homodimer (Hilliard et al., 1998). Although pinA inhibits proteolysis by endopeptidase La, it does not inhibit cleavage of small molecule substrates or hydrolysis of ATP (Hilliard et al., 1998). PinA therefore does not interfere with ATP binding by endopeptidase La and does not appear to block the active site of the peptidase. Studies with deletion mutants of endopeptidase La imply that pinA binds to the N-terminal domain of the peptidase (Roudiak & Shrader, 1998). This endopeptidase domain has no known function, being neither the ATPase nor the endopeptidase domain and absent from all of the crystal structures, which have been derived from fragments of the protein.
Molecular structure	No tertiary structure has been determined. PinA is a 161-residue protein. In keeping with most intracellular proteins, pinA is not known to possess disulfide bonds.
Clan	unassigned

Distribution of family	Bacteria	-
	Archaea	-
	Protozoa	-
	Fungi	-
	Plants	-
	Animals	-
	Viruses	details

Biological functions	Endopeptidase La is one of the major cytoplasmic endopeptidases in Escherichia coli and impairing its activity presumably conveys some advantage to the infecting bacteriophage, perhaps preventing proteolysis of viral proteins prior to phage assembly.
Statistics for family I24	Sequences:	15
	Identifiers:	1
	Identifiers with PDB entries:	0
Downloadable files	Sequence library (FastA format)
	Sequence alignment (FastA format)
	Phylogenetic tree (Newick format)

Other databases	INTERPRO	IPR019506
	PFAM	PF10465

Inhibitors and Homologues	MEROPS ID	Structure
pinA Lon peptidase inhibitor (phage T4)	I24.001	-
Family I24 unassigned peptidases	unassigned	-