Fig. 3From: The functional role of integrins during intra- and extravasation within the metastatic cascadeRepresentation of an αI-domain-containing integrin heterodimer and the distribution of its domains. All integrins contain a ßI domain in the ß subunit, whilst nine out of the 18 integrin α chains contain an αI-domain of around 200 amino acids, inserted between blades two and three of the ß-propeller [35, 157]. The α subunit is formed by a calf-2 (C2), calf-1 (C1) and a thigh domain supporting the seven-bladed ß-propeller [31]. The αI-domain is coordinated by a Mg2+ ion in the metal-ion-dependent adhesion site (MIDAS) and represents the ligand-binding site. The ß subunit contains a MIDAS and ADMIDAS site mediating conformational changes resulting in an active form of the integrin. The ß subunit contains a ßI-domain, a hybrid domain (H), a plexin-semaphorin-integrin (PSI), four cysteine-rich epidermal growth factor repeats (E1–4) and a ß-tail/transmembrane (ß-T) domain [35]. As bi-directional signaling receptors, integrins convey inside-out and outside-in signaling [31]Back to article page