1.H.3. The 4 TMS Amastin (Amastin) Family Amastin is a transmembrane glycoprotein found on the cell surfaces of trypanosomatid parasites. Encoded by a large, diverse gene family, amastin was initially described from the intracellular, amastigote stage of Trypanosoma cruzi and Leishmania donovani. Genome sequences subsequently showed that the amastin repertoire is much larger in Leishmania relative to Trypanosoma. Jackson 2010 sequenced the genomic regions containing amastin loci from two related insect parasites (Leptomonas seymouri and Crithidia sp.) and estimated the phylogeny for these and other amastin sequences. Amastin includes four subfamilies with distinct genomic positions, secondary structures, and evolution, which were already differentiated in the ancestral trypanosomatid. Diversification in Leishmania was initiated from a single ancestral locus on chromosome 34, with rapid derivation of novel loci through transposition and accelerated sequence divergence. This is absent from related organisms showing that diversification occurred after the origin of Leishmania. Some amastin genes may have evolved novel functions crucial to cell function in leishmanial parasites after the acquisition of a vertebrate host (Jackson 2010). Amastins may be virulence genes in Leishmania species (Azizi et al. 2009). Amastins have been used for vaccine development (Bolhassani et al. 2011).
References:
Azizi, H., K. Hassani, Y. Taslimi, H.S. Najafabadi, B. Papadopoulou, and S. Rafati. (2009). Searching for virulence factors in the non-pathogenic parasite to humans Leishmania tarentolae. Parasitology 136: 723-735.
Bolhassani, A., E. Gholami, F. Zahedifard, N. Moradin, P. Parsi, F. Doustdari, N. Seyed, B. Papadopoulou, and S. Rafati. (2011). Leishmania major: Protective capacity of DNA vaccine using amastin fused to HSV-1 VP22 and EGFP in BALB/c mice model. Exp Parasitol 128: 9-17.
Jackson, A.P. (2010). The evolution of amastin surface glycoproteins in trypanosomatid parasites. Mol Biol Evol 27: 33-45.
Slathia, P.S. and P. Sharma. (2018). Conserved epitopes in variants of amastin protein of Trypanosoma cruzi for vaccine design: A bioinformatics approach. Microb. Pathog. 125: 423-430.
Zhu, J., Z.W. Jia, C.Y. Xia, and X.D. Gao. (2020). The Sur7/PalI family transmembrane protein Tos7 (Yol019w) plays a role in secretion in budding yeast. Fungal Genet Biol 144: 103467.
Examples:
TC#	Name	Organismal Type	Example
1.H.3.1.1	Amastin of 174 aas and 4 TMSs in a 1 + 3 TMS arrangement as is typical of members of the Amastin family (Slathia and Sharma 2018).		Amastin of Trypanosoma cruzi

1.H.3.1.10	Uncharacterized protein of 270 aas and 4 distant TMSs in an apparent 2 + 2 TMS arrangement.		UP of Strigomonas culicis

1.H.3.1.11	Uncharacterized protein of 199 aas and 4 TMSs in a 21 + 3 TMS arrangement.		UP of Leishmania guyanensis

1.H.3.1.12	g-amastin of 216 aas and 4 TMSs in a 1 + 2 + 1 arrangement.		*g-Amastin of Crithidia* sp.**

1.H.3.1.13	Amastin-like protein of 250 aas and 4 TMSs in a 1 _ 2 + 1 TMS arrangement.		Amastin-like surface protein of Angomonas deanei

1.H.3.1.14	Amastin-like protein of 249 aas and 4 TMSs in a 1 + 2 + 1 TMS arrangement.		Amastin protein of Leptomonas pyrrhocoris

1.H.3.1.15	Uncharacterized protein of 190 aas and 4 TMSs		UP of Trypanosoma conorhini

1.H.3.1.16	Uncharacterized protein of 194 aas and 4 TMSs in a 1 + 3 TMS arrangement.		UP of Saitozyma podzolica

1.H.3.1.17	Uncharacterized protein of 490 aas and 8 TMSs in a 1 + 3 + 1_ 2 + 1 TMS arrangement. This protein belongs to the Pfam family, PF02681 and the PAP2 (CL0525) clan.		UP of Leishmania major

1.H.3.1.18	Amastin protein, TryB2, of 299 aas with a hydrophilic N-terminal domain followed by a 4 TMS .domain.		*Amastin of Trypanosoma brucei* brucei**

1.H.3.1.19	Amastin protein of 183 aas and 4 TMSs.		Amastin of Leishmania donovani

1.H.3.1.2	Amastin-like protein of 456 aas and 4 C-terminal TMSs in a 1 + 3 TMS arrangement.		Amastin of Trypanosoma brucei

1.H.3.1.3	Amastin-like protein of 221 aas and 4 TMSs in a 1 + 3 TMS arrangement.		Amastin-like protein of Leishmania braziliensis

1.H.3.1.4	Large amastin-like protein of 461 aas and 10 TMSs in a 2 + 1 + 4 + 3 TMS arrangement. This protein may have 2 N-terminal TMSs followed by two 4-TMS Amastin-like domains. The last 4 TMSs show the greatest sequence similarity with shorter amastins.		Large mmastin-like protein of Trypanosoma cruzi

1.H.3.1.5	Putative amastin-like surface protein of 262 aas and 5 or 6 TMSs in a 2 + 3 or 3 + 3 TMS arrangement, respectively.		Amastin-like protein of Leishmania major

1.H.3.1.6	Amastin-like protein of 203 aas and 4 TMSs in a 1 + 2 + 1 TMS arrangement.		Amastin-like protein of Leishmania braziliensis

1.H.3.1.7	Uncharacterized protein of 331 aas and 7 TMSs in a 2 + 2 + 2 + 1 TMS arrangement.		UP of Angomonas deanei

1.H.3.1.8	Amastin-like protein of 380 aas and 8 TMSs in a 1 + 4 + 3 TMS arrangement, possibly with two tandem amastin-like domains.		Internally duplicated amastin domains in Bodo saltans

1.H.3.1.9	Putative amastin protein of 431 aas and 9 TMSs in a 2 + 2 + 2 + 2 + 1 TMS arrangement.		*Amastin-like protein of Phytomonas* sp.**

Examples:
TC#	Name	Organismal Type	Example
1.H.3.2.1	Uncharacterized pali-domain containing protein of 523 aas and 4 TMSs at the N-terminus of the protein in a 1 + 3 TMS arrangement with a long C-terminal hydrophilic domain.		UP of Suhomyces tanzawaensis

1.H.3.2.2	Uncharacterized protein of 580 aas and 4 TMSs in a 1 + 3 arrangement with a long C-terminal hydrophilic domain.		UP of Candida parapsilosis

1.H.3.2.3	Uncharacterized protein of 553 aas and 4 TMSs in a 1 + 3 TMs arrangement followed by a long hydrophilic domain.		UP of Clavispora lusitaniae

1.H.3.2.4	Putative pH signal transduction protein PalI of 561 aas and 4 N-terminal TMSs in a 1 + 3 TMS arrangement followed by a large hydrophilic domain.		PalI protein of Aspergillus flavus

1.H.3.2.5	Uncharacterized protein of 231 aas and 4 TMSs in a 1 + 3 TMS arrangement.		UP of Venustampulla echinocandica

1.H.3.2.6	Uncharacterized protein of 309 aas and 4 TMSs in a 1 + 3 TMs arrangement with a C-terminal hydrophilic domain.		UP of Komagataella pastoris

1.H.3.2.7	Tos7p of 515 aas and 4 N-terminal TMSs in a 1 + 3 TMS arrangement. Tos7 contributes to cell surface-related functions probably as an auxiliary component of the MCC/eisosome complex that interacts with and regulates the secretory pathway (Zhu et al. 2020).		*Tos7 of Saccharomyces cerevisiae* (baker's yeast)**

Examples:
TC#	Name	Organismal Type	Example
1.H.3.3.1	Uncharacterized protein of 367 aas and 4 TMSs in a 1 + 3 TMS arrangement.		UP of Monosiga brevicollis

1.H.3.3.2	Uncharacterized protein of 597 aas and 4 N-terminal TMSs in a 1 + 3 TMS arrangement followed by a large hydrophilic domain that shows extensive sequence similarity with 1.W.6.4.1.		UP of Monosiga brevicollis

1.H.3.3.3	Uncharacterized protein of 262 aas and either 4 or 6 TMSs in a 1 + 3 or 3 + 3 TMS arrangement, respectively.		UP of Salpingoeca rosetta

1.H.3.3.4	Uncharacterized protein of 179 aas and 4 TMSs in a 1 + 2 + 1 TMS arrangement.		UP of Ancylostoma ceylanicum

1.H.3.3.5	Uncharacterized protein of 195 aas and 4 TMSs in a 1 + 2 + 1 TMS arrangement.		UP of Steinernema carpocapsae

1.H.3.3.6	Unharacterized protein of 209 aas and 4 TMSs in a 1 + 3 TMS arrangement.		UP of Caenorhabditis brenneri

Examples:
TC#	Name	Organismal Type	Example
1.H.3.4.1	Uncharacterized protein of 251 aas and 4 TMSs in a 1 + 3 TMS arrangement		UP of Leptomonas pyrrhocoris

1.H.3.4.2	Uncharacterized protein of 227 aas and 4 or 5 TMSs in a 1 + 2 + 1 or 1 + 3 + 1 TMS arrangement.		UP of Trypanosoma theileri

1.H.3.4.3	Uncharacterized protein of 221 aas and 4 TMSs in a 1 + 3 TMS arrangement.		UP of Trypanosoma equiperdum