Toshio  Kamiya, Takashi  Masuko, Dasiel Oscar  Borroto-Escuela, Haruo  Okado, Hiroyasu  Nakata, 
    A Consensus Sequence among Natural Transmembrane Linkers for Single-Polypeptide Chain
(SC) Connection of Two G-Protein-Coupled Receptors in Tandem,
    Journal of Molecular Genetics,
    Volume 13,Issue 1,
    2021,
    Pages 1-45,
    ISSN 2070-4267,
    jmolgene.2021.1.45,
    (https://makhillpublications.co/view-article.php?doi=jmolgene.2021.1.45)
    Abstract: A transmembrane (TM) single-polypeptide
chain (sc) linker that can connect any two class A Gprotein-
coupled receptors (GPCRs) in tandem as a genefusion
strategy has been demonstrated. Here, we report
that a natural TM linker for sc exists that can connect two
GPCRs in tandem. <i>In silico</i> analysis indicated that the
central intervening portion (amino acid residues
311~416) of <i>Exaiptasia diaphana</i> (LOC110241027)
GPCR fusion protein contains a single probable TM
domain and that a consensus sequence, T(I/A/P) (A/S)
(L/N) (I/W/L) (I/A/V) GL (L/G) (A/T) (S/L/G) (I/L) is
conserved between this TM and previously characterized
TM-linkers deriving from the type II TM proteins with a
cytoplasmic N-ter segment, single TM and extracellular
C-ter tail, <i>Caenorhabditis elegans odr4</i> and human CD23.
In addition, to the invertebrate TM-linker, it was
found that in the central intervening region of
tropical bird <i>Opisthocomus hoazin</i> protein
LOC104327099 (XP_009930279.1), TM-linker contains
the consensus sequence. Here, we directed for the first
time, our attention to the natural TM sc linker as a rare
evolutionary event among all mammalian and avian
proteins.
    Keywords: Transmembrane single polypeptide chain linker;oligomerization;adenosine A2A receptor;dopamine D2 receptor; receptor allostery;fusion protein;striatum;supramolecular protein assembly;consensus sequence of
natural scGPCR TM linker