AMMECR1 is a critical gene in the pathogenesis of AMME syndrome. But, little is known about how AMMECR1 is regulated. Here, we showed that many human cell lines expressed AMMECR1. With Phos-tag SDS PAGE analysis, we demonstrated that AMMECR1 was constitutively phosphorylated at Ser16. AMMECR1 was localized in the nucleus. Mutation of Ser16 to alanine did not affect its nuclear localization. The homologs of AMMECR1, PAC688.03c and MTH857, were also nuclear proteins, but they were not phosphorylated when tested in HeLa cells. Therefore, AMMECR1 and its homologs might have atypical nuclear localization sequences.