PROSITE documentation PDOC50213

FAS1/BIgH3 domain profile

The FAS1 or BIgH3 domain is an extracellular module of about 140 amino acid residues. It has been suggested that the FAS1 domain represents an ancient cell adhesion domain common to plants and animals [1]; related FAS1 domains are also found in bacteria [2]. Most FAS1 domain containing proteins are GPI anchored and contain two or four copies of the domain. FAS1 domains of BIgH3 protein mediate cell adhesion throught an interaction with α3/β1 integrin. A short motif (EPDIM), located on the C-teminal side of the fourth domain, is essential for the binding to integrin [3].

The crystal structure of two FAS1 domains (FAS1 3-4) of a fas1 protein have been solved (see <PDB:1O70>) [4]. Each domain consists of seven-stranded wedge and at least five α helices. Two well-ordered N-acetylglucosamine moities attached to a conserved asparagine are located in the interface region between the two FAS1 domains.

Some of the proteins containing a FAS1 domain are listed below.

• Drosophila fasciclin I (fas1) protein. A cell adhesion molecule involved in axon guidance. It is attached to the membrane by a GPI-anchor (4 copies).
• Human TGF-β induced Ig-H3 (BIgH3) protein. Mutation in its FAS1 domains result in corneal distrophy, due to the deposition of insoluble protein aggregates (4 copies).
• Arabidopsis fasciclin-like arabinogalactan proteins (2 copies).
• Volvox major cell adhesion protein (2 copies).
• Bacterial immunogenic protein MPT70 (1 copy).
• Human extracellular matrix protein periostin (4 copies).
• Mammalian stabilin protein (7 copies).

The profile we developed covers the entire FAS1 domain.