1.A.151. The Ubiquitous Insect Chemoreceptor (UICR or 7TMIC) Family Himmel et al. 2023 presented a pipeline for the identification and characterization of distant homologs, and applied it to 7-transmembrane-domain ion channels (7TMICs), a protein group founded by insect odorant and gustatory receptors. Previous sequence and limited structure-based searches identified putatively related proteins, mainly in other animals and plants. However, very few 7TMICs have been identified in non-animal, non-plant taxa. Moreover, these proteins' remarkable sequence dissimilarity made it uncertain whether disparate 7TMIC types (Gr/Or, Grl, GRL, DUF3537, PHTF, and GrlHz) are homologous or convergent, leaving their evolutionary history unresolved. The pipeline identified thousands of new 7TMICs in archaea, bacteria, and unicellular eukaryotes. Using graph-based analyses and protein language models to extract family-wide signatures, we demonstrate that 7TMICs have structure and sequence similarity, supporting homology. Through sequence- and structure-based phylogenetics, eukaryotic 7TMICs were classified into two families (Class-A and Class-B), which are the result of a gene duplication predating the split(s) leading to Amorphea (animals, fungi, and allies) and Diaphoretickes (plants and allies). 7TMICs are a cryptic superfamily, with origins close to the evolution of cellular life.
This family belongs to the Odorant Receptor Channel.
References:
Himmel, N.J., D. Moi, and R. Benton. (2023). Remote homolog detection places insect chemoreceptors in a cryptic protein superfamily spanning the tree of life. Curr. Biol. 33: 5023-5033.e4.
Examples:
TC#	Name	Organismal Type	Example
1.A.151.1.1	*7 TMS ion channel (7TMIC) of 679 aas and 7 TMSs in a 2 or 3 + 2 + 2 + 1 TMS arrangement (Himmel et al.* 2023).**		7TMIC of Tetrahymena thermophila

1.A.151.1.2	Uncharacterized protein of 660 aas and 7 - 10 TMSs in a 2 or 3 + 2 or 3 + 2 or 3 + 1 TMS arrangement.		UP of Marchantia polymorpha

1.A.151.1.3	Uncharacterized protein of 704 aas and 7 or 8 TMSs in a 2 or 3 + 2 + 2 + 1 TMS arrangement.		UP of Moneuplotes crassus

1.A.151.1.4	Uncharacterized protein of 646 aas and probably 7 TMSs in a 2 + 2 + 2 + 1 TMS arrangement within residues 380 - 646.		UP of Stylonychia lemnae

1.A.151.1.5	Uncharacterized protein of 549 aas and 7 or 8 TMSs in a 2 or 3 + 2 + 2 + 1 TMS arrangement.		UP of Blepharisma stoltei

1.A.151.1.6	Uncharacterized protein of 648 aas with 8 TMSs in a 3 + 2 + 2 + 1 TMS arrangement.		UP of Amoeboaphelidium protococcarum

Examples:
TC#	Name	Organismal Type	Example
1.A.151.2.1	Uncharacterized protein of 863 aas and 7 or 8 TMSs in a 2 or 3 + 2 +2 +1 TMS arrangement with the first 6 or 7 occurring within residues 300 -650, and the last TMS at the C-terminus.		UP of Tetrahymena thermophila

1.A.151.2.2	Uncharacterized protein of 648 aas and 7 or 8 TMSs in a 3 + 2 + 2 + 1 TMS arrangement.		UP of Paramecium tetraurelia