PE-PGRS family, N-terminal (IPR000084)

Short name: PE-PGRS_N

Overlapping homologous superfamilies


Domain relationships



The human pathogen Mycobacterium tuberculosis harbours a large number of genes that encode proteins whose N-termini contain the characteristic motifs Pro-Glu (PE) or Pro-Pro-Glu (PPE). A subgroup of the PE proteins contains polymorphic GC-rich sequences (PGRS), while a subgroup of the PPE proteins contains major polymorphic tandem repeats (MPTR). The function of most of these proteins remains unknown [PMID: 19602151]. However, the PE_PGRS proteins from Mycobacterium marinum are secreted by components of the ESX-5 system that belongs to the recently defined type VII secretion systems [PMID: 18981138]. It has also been reported that the PE_PGRS family of proteins contains multiple calcium-binding and glycine-rich sequence motifs GGXGXD/NXUX. This sequence repeat constitutes a calcium-binding parallel beta-roll or parallel beta-helix structure and is found in RTX toxins secreted by many Gram-negative bacteria [PMID: 18267304].

This family is named after a PE motif near to the amino terminus. The carboxyl terminus of this family are variable and fall into several classes. The largest class of PE proteins is the highly repetitive PGRS class which have a high glycine content. The function of these proteins is uncertain but it has been suggested that they may be related to antigenic variation of Mycobacterium tuberculosis [PMID: 9634230].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.