Component of the crb-galla-Xpd (CGX) complex which is essential for proper mitotic chromosome segregation in early embryos. The CGX complex is also required for cell proliferation in developing wing disks. In the CGX complex, acts with crb to recruit Xpd thus forming the functional complex. Component of the CGX complex composed of crb, galla (galla-1 or galla-2) and Xpd. Interacts with crb (via intracellular domain). Is not able to interact with Xpd in the absence of crb. Expressed in a punctate pattern in spindle microtubules during metaphase. Expressed at low levels during larval stages, and at higher levels in pupae and adults (at protein level). Ubiquitously expressed in the wing disk (at protein level). Mutant flies show temperature-sensitive lethality. Prior to cellularization many embryos display signs of incomplete chromosome segregation during mitotic divisions likely due to defective organization of spindle microtubules. The name 'galla' means splitting in Korean and is derived from its role in chromosome segregation. Belongs to the MIP18 family.