SH3 domain binding glutamic acid-rich protein (SH3BGR), also designated 21-glutamic acid-rich protein (21-GARP), is a 239-amino acid protein differentially expressed in heart and skeletal muscle. Its proline-rich region contains the consensus sequence for an SH3-binding domain and its acidic C-terminal region contains a glutamic acid-rich domain which may assume a coiled-coil structure. SH3BGR may be part of a multimeric complex, as it contains 2 functional domains involved in protein-protein interactions. The SH3BGR gene maps proximal to HMG14 on chromosome 21q22.3.
