Water-soluble trans-membrane proteins and methods for the preparation and use thereof

1. A method for producing a water-soluble variant of a G Protein-Coupled Receptor (GPCR), the method comprising:

(1) entering a sequence of the GPCR for analysis;

(2) obtaining a variant of the GPCR, wherein substantially all of Leucine (L), Isoleucine (I), Valine (V), and Phenylalanine (F) in the transmembrane (TM) domain alpha-helical segments (“TM regions”) of the GPCR are substituted, wherein:

(a)

each said Leucine (L) is independently substituted by Glutamine (Q), Asparagine (N), or Serine (S);

(b) each said Isoleucine (I) and said Valine (V) are independently substituted by Threonine (T), Asparagine (N), or Serine (S); and,

(c) each said Phenylalanine is substituted by Tyrosine (Y); and, subsequently,

(3) obtaining an α-helical secondary structure result for the variant to verify maintenance of α-helical secondary structures in the variant;

(4) obtaining a trans-membrane (TM) region result for the variant to verify water solubility of the variant, wherein said water solubility of said variant is verified when said TM region result predicts absence of TM regions or low propensity to form TM regions, based on the sequence of said variant, and,

(5) selecting and producing the variant obtained in step (2) that has maintained α-helical secondary structures according to step (3), and is verified to have water solubility in step (4) as said water-soluble variant of the GPCR.

2. The method of claim 1 , wherein step (3) is performed prior to, concurrently with, or after step (4).

3. The method of claim 1 further comprising performing the method with a data processor.

4. The method of claim 1 , wherein about 96%, 97%, 98%, 99% or 100% of said leucines are substituted by glutamines, about 96%, 97%, 98%, 99% or 100% of said isoleucines are substituted by threonines, about 96%, 97%, 98%, 99% or 100% of said valines are substituted by threonines, or about 96%, 97%, 98%, 99% or 100% of said phenylalanines are substituted by tyrosines.

5. The method of claim 1 , wherein 1, 2, or 3 of said leucines are not substituted, 1, 2, or 3 of said isoleucines are not substituted, 1, 2, or 3 of said valines are not substituted, or 1, 2, or 3 of said phenylalanines are not substituted.

6. The method of claim 1 , wherein the TM regions of the GPCR are predicted using TMHMM 2.0 (TransMembrane prediction using Hidden Markov Models) software module.

7. A non-transitory computer readable medium having stored thereon a sequence of instructions to perform the method of claim 1 .

8. The method of claim 1 , wherein in step (2), all (100% of) said leucines in the TM regions are substituted by glutamines, all (100% of) said isoleucines in the TM regions are substituted by threonines, all (100% of) said valines in the TM regions are substituted by threonines, and all (100% of) said phenylalanines in the TM regions are substituted by tyrosines.

9. The method of claim 1 , wherein all said leucines are substituted by glutamines, all said isoleucines are substituted by threonines, all said valines are substituted by threonines, or all said phenylalanines are substituted by tyrosines.