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.
This family belongs to the Phospholemman/SIMP/Viroporin (PSV) Superfamily.
Examples:
TC#	Name	Organismal Type	Example
1.A.113.1.1	The small integral membrane protein 22 of 81 aas and 1 TM		Small integral membrane protein 22 of Stegastes partitus

1.A.113.1.2	Small integral membrane protein 5 isoform X1 of 119 aas and 1 TM		Small integral membrane protein 5 isoform X1 of Anolis carolinensis

1.A.113.1.3	ELN homologue of unknown function with 158 aas and 2 TMSs		ELN homologue of Alligator mississippiensis (American alligator)

1.A.113.1.4	Small integral membrane DUF4713 protein 22 of 83 aas and 1 TMS		Small membrane protein-22 of Sorex araneus

1.A.113.1.5	Small integral membrane protein 18 of 111 aas and 1 TMS		Protein 18 of Phascolarctos cinereus

Examples:
TC#	Name	Organismal Type	Example
1.A.113.2.1	Uncharacterized protein of 112 aas and 1 TMS.		UP of Scleropages formosus (Asian bonytongue)

1.A.113.2.2	Uncharacterized protein of 112 aas and 1 TMS.		UP of Empidonax traillii

1.A.113.2.3	Uncharacterized protein of 108 aas and 1 TMS.		*UP of Electrophorus electricus* (Electric eel) (Gymnotus electricus)**

Examples:
TC#	Name	Organismal Type	Example
1.A.113.3.1	Uncharacterized protein of 109 aas and 1 TMS.		UP of Apis mellifera

1.A.113.3.2	Uncharacterized protein of 77 aas and 1 TMS.		*UP of Anopheles gambiae* (African malaria mosquito)**

1.A.113.3.3	Uncharacterized protein of 84 aas and 1 TMS.		*UP of Harpegnathos saltator* (Jerdon's jumping ant)**

1.A.113.3.4	Uncharacterized protein of 81 aas and 1 TMS		UP of Helicoverpa armigera

1.A.113.3.5	Uncharacterized protein of 97 aas and 1 TMS		*UP of Nasonia vitripennis* (Parasitic wasp)**

1.A.113.3.6	Uncharacteerized protein of 84 aas and 1 TMS		*UP of Nicrophorus vespilloides* (Boreal carrion beetle)**

1.A.113.3.7	Uncharacterized protein of 87 aas and 1 TMS		*UP of Laodelphax striatella* (small brown planthopper)**

1.A.113.3.8	Uncharacterized protein of 192 aas and 2 putative TMSs.		*UP of Folsomia candida* (Springtail)**

Examples:
TC#	Name	Organismal Type	Example
Examples:
TC#	Name	Organismal Type	Example
1.A.113.5.1	Endoregulin, ELN, also called small integral membrane protein-6, SMIM6, is of 62 aas and 1 TMS. This protein and the other members of the phospholamban family have been designated "micropeptides". Micropeptides function as regulators of calcium-dependent signaling in muscle. The sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA TC# 3.A.3.2.7), is the membrane pump that promotes muscle relaxation by taking up Ca²⁺ into the sarcoplasmic reticulum. It is directly inhibited by three known muscle-specific micropeptides: myoregulin (MLN), phospholamban (PLN) and sarcolipin (SLN). In non muscle cells, there are two other such micopeptides, endoregulin (ELN) and "another-regulin (ALN) (Anderson et al. 2016). Endoregulin is also known as "small integral membrane protein-6" (SMIM6) while ALN is also known as Protein C4 orf3 (C4orf3). These proteins share key amino acids with their muscle-specific counterparts and function as direct inhibitors of SERCA pump activity. The distribution of transcripts encoding ELN and ALN mirrored that of SERCA isoform-encoding transcripts in nonmuscle cell types. Thus, these two proteins are additional members of the SERCA-inhibitory micropeptide family, revealing a conserved mechanism for the control of intracellular Ca²⁺ dynamics in both muscle and nonmuscle cell types (Anderson et al. 2016).		Endoregulin of Homo sapiens

1.A.113.5.2	ELN homologue of 78 aas and 1 TMS.		ELN homologue of Nothobranchius furzeri

1.A.113.5.3	ELN homologue of 75 aas and 1 TMS.		ELN of Larimichthys crocea (large yellow croaker)

1.A.113.5.4	Bacterial ELN homologue of unknown function with 101 aas and 1 TMS		ELN homologue of Desulfobacteraceae bacterium

1.A.113.5.5	ELN homologue of 85 aas and 1 TMS		*ELN homologue of Thermotoga* sp.**

1.A.113.5.6	Small integral membrane protein 6 of 56 aas and 1 TMS, ELN.		ELN of Mus musculus