Ubiquitin-associated and SH3 domain-containing protein A is a protein that in humans is encoded by the UBASH3A gene.

Function: Interferes with CBL-mediated down-regulation and degradation of receptor-type tyrosine kinases. Promotes accumulation of activated target receptors, such as T-cell receptors, EGFR and PDGFRB, on the cell surface. Exhibits negligigle phosphatase activity. May act as a dominant-negative regulator of UBASH3B-dependent dephosphorylation. May inhibit dynamin-dependent endocytic pathways by functionally sequestering dynamin via its SH3 domain.