Core component of multiple SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination of proteins involved in cell cycle progression, signal transduction and transcription. In the SCF complex, serves as a rigid scaffold that organizes the SKP1-F-box protein and RBX1 subunits. May contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. During early metamorphosis, part of the SCF-slmb complex that negatively regulates the InR/PI3K/TOR pathway to activate the pruning of unnecessary larval ddaC dendrites and mushroom body axons (PubMed:24068890). The SCF-slmb complex also regulates asymmetrical division of neuroblasts and inhibits ectopic neuroblast formation partly through SAK and Akt1 (PubMed:24413555). Also part of an SCF complex required for caspase activation during sperm differentiation (PubMed:20392747). Necessary for auditory transduction: plays a role in Johnston's organ organization by acting in the regulation of zip and ck function in scolopidial apical attachment (PubMed:27331610). May function by acting in a Ubr3-mediated pathway that negatively regulates the ubiquitination of zip, consequently affecting its interaction with ck (PubMed:27331610). Protein modification; protein ubiquitination. Component of SCF E3 ubiquitin-protein ligase complexes consisting of Skpa, Cul1, Roc1a and an F-box protein. In larval neuroblast self renewal and asymmetric division, as well as ddaC dendrite and mushroom body axon pruning, the complex contains the F-box protein slmb (SCF-slmb) (PubMed:24068890, PubMed:24413555). In caspase activation during sperm differentiation, the complex contains the F-box protein ntc (PubMed:20392747). Interacts directly with Roc1a (PubMed:11500045). Interacts with Fsn (PubMed:20123973). Interacts with Dlish (PubMed:27692068). Interacts with Cad99C (via the cytoplasmic domain) (PubMed:27331610). Interacts with Sans (PubMed:27331610). In the spermatid, colocalizes with ntc at the actin-based individualization complex and the cystic bulge. Expressed in testis. Neddylated (PubMed:12183637, PubMed:18493598). Deneddylated via its interaction with the COP9 signalosome (CSN) complex (PubMed:12183637). Severe dendrite pruning defects in ddaC neurons at 16 hours after puparium formation (APF) and axon pruning defects in mushroom body gamma neurons at 24 hours APF. RNAi-mediated knockdown results in a significant increase in Akt1 protein levels and activity in ddaC somas (PubMed:24068890). In the larval brain there is a large increase in the number of neuroblasts, 40% of which show a spindle misorientation at metaphase (PubMed:24413555). RNAi-mediated knockdown results in apical detachment of scolopidial cells in Johnston's organ (PubMed:27331610). Belongs to the cullin family.