Pilus

Proteinaceous hair-like appendage on the surface of bacteria

A pilus (Latin for 'hair'; pl.: pili) is a hair-like cell-surface appendage found on many bacteria and archaea. The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All conjugative pili are primarily composed of pilin – fibrous proteins, which are oligomeric.

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