There are a number of ELISA Kits available for the measurement of IR-A, another term for the human protein, insulin receptor. Other synonyms may include: IR, CD220, and HHF5. It is encoded by the INSR gene to yield a protein 1382 amino acids in length and 156.3 kDa in size. However, there are up to 2 reported isoforms. The protein, an enzyme, is categorized into the Protein kinase superfamily, Tyr protein kinase family, Insulin receptor subfamily. Versions of IR-A are present in other organisms, including: Mouse, Rat.