The SH2 domains of SH2B beta (Uniprot isoform Q9NRF2-2) binds JAK2 at Tyr813. SH2B beta is able to homodimerize while bound to JAK2 molecules, suggesting that SH2B binding and dimerization may help induce JAK2 transactivation (Nishi et al. 2005). Computational modeling suggests that SH2B beta can enhance Jak2 activation (Barua et al. 2009). The relevance of this for PRLR signalling has yet to be demonstrated.