Its gene lies within the major histocompatibility complex class I region on chromosome 6. Studies of a similar rat protein suggest that RNF39 plays a role in an early phase of synaptic plasticity. Its gene lies within the major histocompatibility complex class I region on chromosome 6.This gene lies within the major histocompatibility complex class I region on chromosome 6. Studies of a similar rat protein suggest that this gene encodes a protein that plays a role in an early phase of synaptic plasticity. Alternative splicing results in three transcript variants encoding different isoforms.