1.A.113.  The Small Integral Membrane Protein (SIMP) Family

Members of the Small Integral Membrane Protein (SIMP) Family usually have just one TMS, but one of them (TC# 1.A.113.1.3) has two TMSs due to an internal duplication.  They may be homologous to proteins of the same sizes and topologies as the members of families 1.A.50, 1.A.95 and 1.A.100.