These repeats are found in many cyanobacterial proteins. The repeats were first identified in hglK [1]. The function of these repeats is unknown. The structure of this repeat has been predicted to be a beta-helix [2]. The repeat can be approximately described as A(D/N)LXX, where X can be any amino acid.

1: The hglK gene is required for localization of heterocyst-specific glycolipids in the cyanobacterium Anabaena sp. strain PCC 7120. Black K, Buikema WJ, Haselkorn R; J Bacteriol 1995;177:6440-6448. PMID:7592418

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

3: Characterisation of an Arabidopsis cDNA encoding a thylakoid lumen protein related to a novel 'pentapeptide repeat' family of proteins. Kieselbach T, Mant A, Robinson C, Schroder WP; FEBS Lett 1998;428:241-244. PMID:9654141