Involved in EGFR trafficking, acting as negative regulator of endocytic EGFR internalization at the plasma membrane. Interacts with RBFOX1 (By similarity). Monomer. Can also form homodimers. Interacts with polyribosomes (By similarity). Interacts with EGFR (By similarity). Interacts with SH3GL3 (By similarity). Interacts with SH3GL2, SH3KBP1 and CBL (PubMed:18602463). Interacts with ATXN2L (By similarity). Expressed in the heart, lung, liver, kidney, skeletal muscle, spleen and intestine. Predominant expression was seen in the brain where a high level expression was found in the pyramidal cortical neurons, large brain stem neurons and cerebellar Purkinje cells. All three isoforms were found in all the tissues except skeletal muscle where only isoform 1 was found. Detectable at 8-16 dpc. Lowest expression was seen at 8 dpc. Belongs to the ataxin-2 family.