May be involved in axonal outgrowth as component of the network of molecules that regulate cellular morphology and axon guidance machinery. May participate in the transport of mitochondria and other cargos along microtubules (By similarity). Homodimer. Interacts with the NH2-terminal variable region (V1) of PKC zeta and weakly with that of PKC epsilon. Interacts with UBE4B and SAP30L (By similarity). Interacts with SCOC and ULK1; SCOC interferes with ULK1-binding to FEZ1 (By similarity). Directly interacts with SCOC and UVRAG. Stabilizes the interaction between SCOC and UVRAG during amino acid starvation (By similarity). Colocalizes with both, alpha- and gamma-tubulin. Translocated from the plasma membrane to the cytoplasm by activation of the PKC zeta (By similarity). Phosphorylated by protein kinase C zeta; which enhances interaction with UBE4B and polyubiquitination. Polyubiquitinated in a UBE4B-dependent manner; which does not lead to proteasomal degradation and may be important for neurogenic activity. Polyubiquitin linkage seems to be mainly through Lys-26 (By similarity). Belongs to the zygin family.