These repeats are found in many mycobacterial proteins. These repeats are most common in the Pfam:PF00823 family of proteins, where they are found in the MPTR subfamily of PPE proteins. The function of these repeats is unknown. The repeat can be approximately described as XNXGX, where X can be any amino acid. These repeats are similar to Pfam:PF00805 [1], however it is not clear if these two families are structurally related.

1: Structure and distribution of pentapeptide repeats in bacteria. Bateman A, Murzin A, Teichmann SA; Protein Sci 1998;7:1477-1480. PMID:9655353

2: Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence. Cole ST, Brosch R, Parkhill J, Garnier T, Churcher C, Harris D, Gordon SV, Eiglmeier K, Gas S, Barry CE 3rd, Tekaia F, Badcock K, Basham D, Brown D, Chillingworth T, Connor R, Davies R, Devlin K, Feltwell T, Gentles S, Hamlin N, Holroyd S, Hornsby T, Jage Nature 1998;393:537-544. PMID:9634230