Contributes to endodermal integrity and adhesion between the midgut epithelium and the surrounding visceral muscle. Essential for migration of the primordial midgut cells and for maintaining, but not establishing, cell polarity in the midgut epithelium. Can only partially compensate for the loss of beta-PS integrin during primordial midgut cell migration. The two beta subunits mediate midgut migration by distinct mechanisms: beta-PS requires rhea/Talin and beta-nu does not. Integrin alpha-PS3/beta-nu is required for effective phagocytosis of apoptotic cells during embryonic development and for the phagocytic elimination of S.aureus by mediating the binding of S.aureus peptidoglycan to larval hemocytes, which probably activates a signaling pathway involving Rac1 and Rac2. Not required for the production of antimicrobial peptides during S.aureus. Upon activation by LanA, integrin alpha-PS3/beta-nu activates Fak in presynapsis to suppress neuromuscular junction (NMJ) growth during larval development and during low crawling activity, but not during higher-crawling conditions. Mediates, together with LanA, glutamate receptor-modulated NMJ growth. Heterodimer of an alpha and a beta subunit. Interacts with scb/alpha-PS3. Expression is confined to the developing midgut endoderm and its precursors during embryogenesis. In the larvae, expression is concentrated in the midgut imaginal disks. Expressed in embryonic and larval hemocytes (at protein level). Expressed throughout development. Highest expression occurs during 12-15 hours of embryonic development (at protein level). Homozygous mutant flies are viable and fertile. Mutant embryos show reduced level of phagocytosis, but normal level of hemocytes or apoptosis. At NMJ, mutant larvae show normal patterns of synaptic proteins but increased branch length, bouton number and quantal content in basal synaptic transmission recording. Belongs to the integrin beta chain family.