Alpha4, or Immunoglobulin (CD79A) binding protein 1, is a human gene encoded by IGBP1. It may also be known as: Immunoglobulin-binding protein 1; B-cell signal transduction molecule alpha 4; Protein alpha-4; CD79a-binding protein 1; Protein phosphatase 2/4/6 regulatory subunit; Renal carcinoma antigen NY-REN-16; alpha 4; ALPHA-4; IBP1. The encoded protein has an amino acid length of 339 and a mass of 39.2 kDa. Other isoforms may exist. Alpha4 is a member of the IGBP1/TAP42 family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog, Chicken.