301 3UWJ I-H [I-H]>H: M32+F34+K36+S(36A)+QEL(38-40)+L65+R67+RTRY(73-76)+EKI(80-82)+M84+Q151 [I-H]>I: DFEEIP(55-60)+EYLQ(62-65) The site residues were obtained through computing contacts by a distance ≤ 4Å. 302 4BAO D-B [D-B]>B: M53+F55+K57+QEL(60-62)+L96+R98+RTRY(104-107)+EKI(112-114)+M116+Q186 [D-B]>D: DFEEIP(355-360)+EYL(362-364) The site residues were obtained through computing contacts by a distance ≤ 4Å. 303 4E7R G-J:2, H-I:4 [G-J]>G: F1034+Q1038+L1040+L1065+R1067+RTRY(1073-1076)+EKI(1080-1082) [H-I]>H: F34+Q38+L40+L65+R67+RTRY(73-76)+EKI(80-82) [G-J]>J: DFEEIP(1555-1560)+YL(1563,1564) [H-I]>I: DFE(555-557)+IP(559,560)+YL(563,564) 304 4LOY I-H [I-H]>H: M32+F34+K36+S(36A)+QEL(38-40)+L65+R67+RTRY(73-76)+N78+EKI(80-82)+M84 [I-H]>I: DFEEIP(55-60)+EYL(62-64) The site residues were obtained through computing contacts by a distance ≤ 4Å. 305 4N3L I-H [I-H]>H: M32+F34+K36+S(36A)+QEL(38-40)+L65+R67+RTRY(73-76)+EKI(80-82)+M84+Q151 [I-H]>I: DFEEIP(55-60)+EYL(62-64) The site residues were obtained through computing contacts by a distance ≤ 4Å. 306 4NZE I-H [I-H]>H: M32+F34+K36+QEL(38-40)+L65+R67+RTRY(73-76)+EKISM(80-84)+Q151 [I-H]>I: FEEIP(56-60)+EY(62,63) The site residues were obtained through computing contacts by a distance ≤ 4Å. 307 2L29 A-B:1 [A-B]>A: YSKS(1542-1545)+F1567+QT(1569,1570)+I1572+P1597+PS(1599,1600)+S1602+L1629+K1631 [A-B]>B: R3+GE(11,12)+DT(15,16)+QF(18,19)+GD(22,23)+SCDL(50-53)+E57 308 2V5P A-D:2, B-C:3 [A-D]>A: YSE(1542-1544)+F1567+QT(1569,1570)+P1597+PS(1599,1600)+L1629+K1631+L1636 [B-C]>B: YSE(1542-1544)+FGQT(1567-1570)+I1572+P1597+PS(1599,1600)+L1629+K1631 [A-D]>D: E6+L8+E12+D15+QF(18,19)+GD(22,23)+CDL(51-53)+E57 [B-C]>C: E6+L8+GE(11,12)+DT(15,16)+QF(18,19)+GD(22,23)+CDL(51-53)+E57 309 3EHT A-B:1 [A-B]>A: LI(50,51)+RV(96,97)+Y99+Q103 [A-B]>B: R35+LMEII(37-41)+NH2(42) 310 3EHU A-C:2, B-D:3, A-D:4, B-C:5 [A-C]>A: LI(50,51)+FY(72,73)+V75+Y77+RV(96,97)+Y99+E104 [B-D]>B: LI(50,51)+FY(72,73)+V75+Y77+RV(96,97)+Y99+E104 [A-D]>A: I40+L50 [B-C]>B: L50 [A-C]>C: QA(30,31)+N34+LMEII(37-41)+NH2(42) [B-D]>D: QA(30,31)+N34+LMEII(37-41)+NH2(42) [A-D]>D: I41 [B-C]>C: I40 311 1R2B(196) A-C:2, A-D:3, B-C:4, B-D:5 [A-C]>A: MAC(51- 53)+G55+HV(116,117)+T120+K123 [A-D]>A: DSQIQFTRH(6-14)+DV(17,18)+LN(20,21)+NR(23,24)+SR(27,28) [B-C]>B: DSQIQFTRH(6-14)+DV(17,18)+N21+R24+R28 [B-D]>B: MACSG(51-55)+Y58+HV(116,117)+T120+K123 [A-C]>C: E1420+RSIH(1423-1426) [A-D]>D: VATVKEAGRSIHEIPR(1415-1430) [B-C]>C: S0+VATVKEAGRSIHEIPR(1415-1430) [B-D]>D: E1420+RSIH(1423-1426)+I1428 312 3BIM(196) [A-I]:5, [B-J]:6, [C-K]:7, [E-M]:8, [G-O]:9, [H-P]:10, [A-J]:11, [B-I]:12, [D-K]:13, [F-M]:14, [G-P]:15, [H-O]:16, [A-N]:17, [C-L]:23, [E-N]:24, [C-N]:25, [D-L]:26, [F-N]:27, [D-N]:28, [E-K]:29 [A-I]>A: MACSG(51-55)+Y58+MEH(114- 116)+T120 [B-J]>B: MACSG(51- 55)+Y58+EH(115,116)+T120 [C-K]>C: MACSG(51-55)+Y58+EH(115,116) [E-M]>E: MACSG(51- 55)+Y58+Q113+EH(115,116) [G-O]>G: MACSG(51- 55)+Y58+R94+EH(115,116) [H-P]>H: MACSG(51-55)+Y58+EH(115,116) [A-J]>A: DSQIQFTR(6-13)+D17+N21+R24+R28 [B-I]>B: DSQIQFTR(6-13)+D17+N21+RL(24,25)+R28 [D-K]>D: D6+QIQFTR(8-13)+D17+N21+R24+R28 [F-M]>F: DSQIQFTR(6-13)+D17+N21+RL(24,25)+R28 [G-P]>G: SQIQFTR(7-13)+D17+N21+R24+R28 [H-O]>H: DSQIQFTR(6-13)+D17+N21+RL(24,25)+R28 [A-N]>A: Q64 [C-L]>C: QIQFTR(8-13)+D17+N21+R24+R28 [E-N]>E: DSQIQFTR(6- 13)+D17+N21+RL(24,25)+R28 [C-N]>C: T62+Q64 [D-L]>D: MACSG(51-55)+Y58+EH(115,116) [F-N]>F: MACSG(51- 55)+Y58+EH(115,116)+T120 [D-N]>D: R28 [E-K]>E: S27+D29+V35+Q42+R44 A-I]>I: S503+PSSW(506-509)+P512 [B-J]>J: S503+PSSW(506-509)+P512 [C-K]>K: PSSW(506-509)+V511 [E-M]>M: PSSW(506-509)+VP(511,512) [G-O]>O: PSSW(506-509)+VP(511,512) [H-P]>P: PSSW(506-509)+P512 [A-J]>J: RS(498,499)+IIST(501,504)+PS(506,507)+WVVP(509-512) [B-I]>I: RSEIIST(498-504)+PS(506,507)+WVVP(509-512)+P514 [D-K]>K: RSEIISTAPS(498-507)+WVVPGP(509-514) [F-M]>M: RSEIIST(498-504)+PS(506,507)+WVVPGP(509-514) [G-P]>P: RSEIISTAPS(498-507)+WVVPGP(509-514) [H-O]>O: RSEIISTA(498-505)+S507+WVVP(509-512)+P514 [A-N]>N: G513 [C-L]>L: SEIISTA(499-505)+PS(506,507)+WVVPG(509-513) [E-N]>N: SEIIST(499-504)+PS(506,507)+WVVPG(509-513) [C-N]>N: P512+P514 [D-L]>L: PSSW(506-509)+VP(511,512) [F-N]>N: PSSW(506-509)+VP(511,512) [D-N]>N: P514 [E-K]>K: PSSW(506-509)+P512 313 2OSL 314 4QT8 A-C:2, B-D:3, A-D:4 [A-C]>A: AL(128,129)+E190+GQASY(192-196)+R220+KA(222,223)+V233+TEPE(286-289)+H424 [B-D]>B: D64+A128+E190+GQASY(192-196)+R220+KA(222,223)+TEPE(286-289)+H424 [A-D]>A: PG(644,646) [A-C]>C: RQ(521,522)+SSCH(525-528)+S565+Q568+R639+R641+E644+E658+PNR(681-683) [B-D]>D: RQ(521,522)+SSCH(525-528)+S565+Q568+RR(637,639)+E644+E658+PNR(681-683) [A-D]>D: Q502+GE(533,535)+P556 315 4QT8 A-C:2, B-D:3, A-D:4 [A-C]>A: AL(128,129)+E190+GQASY(192-196)+R220+KA(222,223)+V233+TEPE(286-289)+H424 [B-D]>B: D64+A128+E190+GQASY(192-196)+R220+KA(222,223)+TEPE(286-289)+H424 [A-D]>A: PG(644,646) [A-C]>C: RQ(521,522)+SSCH(525-528)+S565+Q568+R639+R641+E644+E658+PNR(681-683) [B-D]>D: RQ(521,522)+SSCH(525-528)+S565+Q568+RR(637,639)+E644+E658+PNR(681-683) [A-D]>D: Q502+GE(533,535)+P556 316 3M17 A-I,C-J,E-K,G-L,G-K [A-i]>A:A81+GG(83,84)+Y88+LN(112,113)+E115+WPE(131-133) [C-J]>C:ALGG(81-84)+Y88+LN(112,113)+E115+WPE(131-133) [E-K]>E:ALGG(81-84)+Y88+LN(112,113)+E115+WPE(131-133) [G-L]>G:ALGG(81-84)+Y88+LN(112,113)+E115+WPE(131-133)+A136 [G-K]>G:QP(261,262) [A-I]>I:TGHFG(Sar)(4-9)+Y(11) [C-J]>J:TGHFG(Sar)(Mle)Y(4-11)+(LE)13 [E-K]>K:TGHFG(Sar)(Mle)Y(4-11) [G-L]>L:TGHF(4-7)+(Sar)9+Y11+(LE)13 [G-K]>K:C13+(NH)214 The consensus motif was discovered Using peptide phage display screening, Gly-His-Phe-Gly-Gly-X-Tyr, where X is preferably a hydrophobic amino acid. The motif is enclosed by a cysteine disulfide loop forming an 11-amino acid loop including the cysteines. The peptide was optimized for inhibition of IgG binding to FcRn and stability in plasma, resulting in monomeric peptide1 SYN1327 and dimeric peptide3 SYN1436. The structures of peptides 1 and 3 in complex with degshFcRn and diffraction data have been deposited with the RCSB Protein Data Bank (entry IDs: 3M17 and 3M1B,respectively). 317 3M1B A-I,C-J [A-I]>A:ALGG(81-84)+Y88+LN(112,113)+E115+WPE(131-133) [C-J]>C:GG(83,84)+Y88+L112+E115+WPE(131-133)+A136 [A-I]>I:TGHFG(Sar)(4-9)+Y11 [C-J]>J:TGHF(104-107)+Y111 The consensus motif was discovered Using peptide phage display screening, Gly-His-Phe-Gly-Gly-X-Tyr, where X is preferably a hydrophobic amino acid. The motif is enclosed by a cysteine disulfide loop forming an 11-amino acid loop including the cysteines. The peptide was optimized for inhibition of IgG binding to FcRn and stability in plasma, resulting in monomeric peptide1 SYN1327 and dimeric peptide3 SYN1436. The structures of peptides 1 and 3 in complex with degshFcRn and diffraction data have been deposited with the RCSB Protein Data Bank (entry IDs: 3M17 and 3M1B,respectively). 318 2FYL A-B:1 [A-B]>B:R16+I18+LDD(26,28)+S37+CA(53,54)+R57+I59+D66+D68+C71+DA(73,74)+G79+H82 [A-B]>A:R21+K24+Q27+EK(30,31)+R34+L57+K60+LD(64,65)+E74+GK(92,93) 319 4KM6 320 4KM7 321 4KMX 322 4LRH 323 5TZQ 324 3LB6 A-C:1,A-D:2,B-D:3 [A-C]>A: R11+E15+M33+DTKIE(87-91)+L101+KK(104,105)+FREG(107-110) [A-D]>A: EGR(109-111) [B-D]>B: R11+IE(14,15)+V18+M33+DTKIE(87-91)+101L+KK(104,105)+FREG(107-110) [A-C]>A: R11+E15+M33+DTKIE(87-91)+L101+KK(104,105)+FREG(107-110) [A-D]>A: EGR(109-111) [B-D]>B: R11+IE(14,15)+V18+M33+DTKIE(87-91)+101L+KK(104,105)+FREG(107-110)