Alignment of zebrafish β1 sequences (β1–1, β1–2, β1–3, β1tr-1, β1tr-2 and β1tr-3) with human β1. The alignment was performed using ClustalW. Protein domains are annotated: PSI, plexin/semaphorin/integrin; EGF, epidermal growth factor; βTD, β terminal domain; TM transmembrane; cyto, cytoplasmic domain. MIDAS (M), ADMIDAS (A) and LIMBS (L) cation binding residues in the A domain are shown. Red underline indicates the position of the βB-βC loop, black underline indicates the position of the βD-α5 loop in the A domain. Sequence identities are indicated by *, conservative substitutions by :, semi-conservative substitutions by.