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Table 4 Several conserved sequence motifs in TMTCs are related to DPM binding and divalent metal ion coordination

From: Conserved sequence motifs in human TMTC1, TMTC2, TMTC3, and TMTC4, new O-mannosyltransferases from the GT-C/PMT clan, are rationalized as ligand binding sites

Motif

Residues

TMTC1

TMTC2

TMTC3

TMTC4

M1 (red)

DD in EL1

D

52

26

31

45

D

53

27

32

46

M2 (orange)

SHKSYRP in EL1

mannose

S

88A

61C

66B

80A

H

89A

62B

67A

81A

K

90B

63C

68A

82A

S

91A

64A

69B

83A

Y

92C

65

70B

84B

R

93C

66

71

85A

P

94

67

72

86A

M3 (yellow)

RxD in EL2

R

167

139A

143

172C

D

169

141A

145B

174

M4 (green)

KE(T/Q) xxT in EL3

K

219A

186A

188A

221A

E

220A

187A

189A

222A

T/Q

221(T)A

188(Q)A

190(Q)A

223(Q)A

T

224A

191B

193B

226C

M5 (blue)

DW in EL4

D

330A

293A

303A

338A

W

331

294A

304A

339A

M6 (violet)

PxxP in TM9

P

386A

404C

358A

394C

P

389B

407A

361A

397B

M7 (pink)

ERxxY in EL5

E

403A

421A

375A

411

R

404C

422A

376C

412

Y

407C

425C

379

415B

  1. Conserved residues present in the vicinity of the ligand dolichyl-phosphate-mannose (DPM) are part of seven motifs M1-M7 in the TMTC family protein sequences. For each motif, the actual sequence, the location (loop number or TM number), loop coloring in Fig. 4 and the residue numbers in TMTC1/2/3/4 respectively are listed. If at least one atom of the residue is within 5 Å, 6 Å or 7 Å of any atom of DPM, the respective residue is marked with the corresponding subscript “A”, “B” or “C”. In bold, we indicate residues in M4 and M5 observed for coordinating the divalent metal ions. We find motifs M2 and M3 largely involved in mannose interactions, M6 provides for the dolichyl tail, and M4, M5 and M7 are important for interaction with the phosphate