Polypeptides

1. A CAIX binding polypeptide, comprising a CAIX binding motif BM, which motif consists of the amino acid sequence:

i)

(SEQ ID NO: 369)

EX 2 X 3 X 4 AX 6 X 7 EIX 10  X 11 LPNLX 16 X 17 X 18 QX 20  X 21 AFIX 25 X 26 LWD 

wherein, independently from each other,

X 2 is selected from D, H, N, Q and W;

X 3 is selected from I, L, Q, R, and W;

X 4 is selected from A, F, W and Y;

X 6 is selected from A, G and S;

X 7 is selected from G, I, V and W;

X 10 is selected from A, D, E, G, N, Q, R, S and T;

X 11 is selected from D, E and S;

X 16 is selected from N and T;

X 17 is selected from A, D, E, I, Q, T and V;

X 18 is selected from A, D, E, F, G, H, N, Q, R, S and Y;

X 20 is R;

X 21 is selected from D, H and N;

X 25 is Y;

X 26 is selected from K and S.

2. The CAIX binding polypeptide according to claim 1 , wherein sequence i) fulfills at least seven of the twelve conditions I-XII:

I. X 2 is N;

II. X 3 is selected from I and L;

III. X 4 is F;

IV. X 6 is G;

V. X 7 is W;

VI. X 10 is selected from D and S;

VII. X 11 is D;

VIII. X 16 is T;

IX. X 17 is selected from E and D;

X. X 18 is selected from D, Y, E and S;

XI. X 21 is N; and

XII. X 26 is K.

3. The CAIX binding polypeptide according to claim 1 , wherein sequence i) is selected from SEQ ID NO:1-44, 46-47, 50-56, 58-61, 63, 65-68, 70, 72, 74-84, 86-87, 90-93, 97-99, 102, 105-108, 110-111 and 113.

4. The CAIX binding polypeptide according to claim 1 , wherein said CAIX binding motif forms part of a three-helix bundle protein domain.

5. The CAIX binding polypeptide according to claim 1 , which comprises the amino acid sequence:

iii)

(SEQ ID NO: 371)

K- [BM] -DPSQS X a X b LLX c  EAKKL NDX d Q;

wherein

[BM] is an CAIX binding motif as defined in claim 1 ;

X a is selected from A and S;

X b is selected from N and E;

X c is selected from A, S and C;

X d is selected from A and S.

6. The CAIX binding polypeptide according to claim 5 , wherein sequence iii) is selected from any one of SEQ ID NO:114-157, 160-161, 163-169, 171-174, 176, 178-181, 183, 185, 187-197, 199-200, 203-206, 210-212, 215, 218-221, 223-224 and 226.

7. The CAIX binding polypeptide according to claim 1 , which comprises the amino acid sequence:

v)

(SEQ ID NO: 384)

VDAKYAK- [BM] -DPSQSSELLSEAKKLNDSQAPK;

wherein [BM] is an CAIX binding motif as defined in claim 1 .

8. The CAIX binding polypeptide according to claim 7 , in which sequence v) is selected from SEQ ID NO:227-270, 272-273, 276-282, 284-287, 289, 291-294, 296, 298, 300-310, 312-313, 316-319, 323-325, 328, 331-334, 336-337 and 339.

9. A fusion protein or conjugate comprising

a first moiety consisting of CAIX binding polypeptide according to claim 1 ; and

a second moiety consisting of a polypeptide having a desired biological activity.

10. A polynucleotide encoding a polypeptide according to claim 1 .

11. A composition comprising a CAIX binding polypeptide according to claim 1 and at least one pharmaceutically acceptable excipient or carrier.

12. A method of detecting CAIX comprising contacting a sample suspected to contain CAIX with the CAIX binding polypeptide according to claim 1 ; and detecting the binding of the CAIX binding polypeptide to indicate the presence of CAIX in the sample.

13. The CAIX binding polypeptide according to claim 3 , wherein sequence i) is selected from SEQ ID NO:1-14.

14. The CAIX binding polypeptide according to claim 13 , wherein sequence i) is selected from SEQ ID NO:1-4.

15. The CAIX binding polypeptide according to claim 6 , wherein sequence iii) is selected from any one of SEQ ID NO:114-127.

16. The CAIX binding polypeptide according to claim 15 , wherein sequence iii) is selected from any one of SEQ ID NO:114-117.

17. The CAIX binding polypeptide according to claim 8 , in which sequence v) is selected from SEQ ID NO:227-240.

18. The CAIX binding polypeptide according to claim 17 , in which sequence v) is selected from SEQ ID NO:227-230.

19. The method of claim 12 wherein the CAIX binding polypeptide is a component of a fusion protein or a conjugate.