diff --git a/packages/proto-signing/scripts/define-proto.sh b/packages/proto-signing/scripts/define-proto.sh
index ed906572..3b5017f3 100755
--- a/packages/proto-signing/scripts/define-proto.sh
+++ b/packages/proto-signing/scripts/define-proto.sh
@@ -20,6 +20,7 @@ protoc \
   "$COSMOS_PROTO_DIR/cosmos/bank/v1beta1/bank.proto" \
   "$COSMOS_PROTO_DIR/cosmos/bank/v1beta1/tx.proto" \
   "$COSMOS_PROTO_DIR/cosmos/crypto/multisig/v1beta1/multisig.proto" \
+  "$COSMOS_PROTO_DIR/cosmos/crypto/multisig/keys.proto" \
   "$COSMOS_PROTO_DIR/cosmos/crypto/secp256k1/keys.proto" \
   "$COSMOS_PROTO_DIR/cosmos/tx/v1beta1/tx.proto" \
   "$COSMOS_PROTO_DIR/cosmos/tx/signing/v1beta1/signing.proto" \
diff --git a/packages/proto-signing/src/codec/cosmos/crypto/multisig/keys.ts b/packages/proto-signing/src/codec/cosmos/crypto/multisig/keys.ts
new file mode 100644
index 00000000..6d692d92
--- /dev/null
+++ b/packages/proto-signing/src/codec/cosmos/crypto/multisig/keys.ts
@@ -0,0 +1,106 @@
+/* eslint-disable */
+import { Any } from "../../../google/protobuf/any";
+import Long from "long";
+import _m0 from "protobufjs/minimal";
+
+export const protobufPackage = "cosmos.crypto.multisig";
+
+/**
+ * LegacyAminoPubKey specifies a public key type
+ * which nests multiple public keys and a threshold,
+ * it uses legacy amino address rules.
+ */
+export interface LegacyAminoPubKey {
+  threshold: number;
+  publicKeys: Any[];
+}
+
+const baseLegacyAminoPubKey: object = { threshold: 0 };
+
+export const LegacyAminoPubKey = {
+  encode(message: LegacyAminoPubKey, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
+    if (message.threshold !== 0) {
+      writer.uint32(8).uint32(message.threshold);
+    }
+    for (const v of message.publicKeys) {
+      Any.encode(v!, writer.uint32(18).fork()).ldelim();
+    }
+    return writer;
+  },
+
+  decode(input: _m0.Reader | Uint8Array, length?: number): LegacyAminoPubKey {
+    const reader = input instanceof Uint8Array ? new _m0.Reader(input) : input;
+    let end = length === undefined ? reader.len : reader.pos + length;
+    const message = { ...baseLegacyAminoPubKey } as LegacyAminoPubKey;
+    message.publicKeys = [];
+    while (reader.pos < end) {
+      const tag = reader.uint32();
+      switch (tag >>> 3) {
+        case 1:
+          message.threshold = reader.uint32();
+          break;
+        case 2:
+          message.publicKeys.push(Any.decode(reader, reader.uint32()));
+          break;
+        default:
+          reader.skipType(tag & 7);
+          break;
+      }
+    }
+    return message;
+  },
+
+  fromJSON(object: any): LegacyAminoPubKey {
+    const message = { ...baseLegacyAminoPubKey } as LegacyAminoPubKey;
+    message.publicKeys = [];
+    if (object.threshold !== undefined && object.threshold !== null) {
+      message.threshold = Number(object.threshold);
+    } else {
+      message.threshold = 0;
+    }
+    if (object.publicKeys !== undefined && object.publicKeys !== null) {
+      for (const e of object.publicKeys) {
+        message.publicKeys.push(Any.fromJSON(e));
+      }
+    }
+    return message;
+  },
+
+  toJSON(message: LegacyAminoPubKey): unknown {
+    const obj: any = {};
+    message.threshold !== undefined && (obj.threshold = message.threshold);
+    if (message.publicKeys) {
+      obj.publicKeys = message.publicKeys.map((e) => (e ? Any.toJSON(e) : undefined));
+    } else {
+      obj.publicKeys = [];
+    }
+    return obj;
+  },
+
+  fromPartial(object: DeepPartial<LegacyAminoPubKey>): LegacyAminoPubKey {
+    const message = { ...baseLegacyAminoPubKey } as LegacyAminoPubKey;
+    message.publicKeys = [];
+    if (object.threshold !== undefined && object.threshold !== null) {
+      message.threshold = object.threshold;
+    } else {
+      message.threshold = 0;
+    }
+    if (object.publicKeys !== undefined && object.publicKeys !== null) {
+      for (const e of object.publicKeys) {
+        message.publicKeys.push(Any.fromPartial(e));
+      }
+    }
+    return message;
+  },
+};
+
+type Builtin = Date | Function | Uint8Array | string | number | undefined | Long;
+export type DeepPartial<T> = T extends Builtin
+  ? T
+  : T extends Array<infer U>
+  ? Array<DeepPartial<U>>
+  : T extends ReadonlyArray<infer U>
+  ? ReadonlyArray<DeepPartial<U>>
+  : T extends {}
+  ? { [K in keyof T]?: DeepPartial<T[K]> }
+  : Partial<T>;
diff --git a/packages/proto-signing/src/pubkey.ts b/packages/proto-signing/src/pubkey.ts
index faa88ac4..ebf9f0c5 100644
--- a/packages/proto-signing/src/pubkey.ts
+++ b/packages/proto-signing/src/pubkey.ts
@@ -1,27 +1,42 @@
 /* eslint-disable @typescript-eslint/naming-convention */
-import { encodeSecp256k1Pubkey, SinglePubkey as AminoPubKey } from "@cosmjs/amino";
+import {
+  encodeSecp256k1Pubkey,
+  isMultisigThresholdPubkey,
+  isSecp256k1Pubkey,
+  Pubkey,
+  SinglePubkey,
+} from "@cosmjs/amino";
 import { fromBase64 } from "@cosmjs/encoding";
+import { Uint53 } from "@cosmjs/math";
 
+import { LegacyAminoPubKey } from "./codec/cosmos/crypto/multisig/keys";
 import { PubKey } from "./codec/cosmos/crypto/secp256k1/keys";
 import { Any } from "./codec/google/protobuf/any";
 
-export function encodePubkey(pubkey: AminoPubKey): Any {
-  switch (pubkey.type) {
-    case "tendermint/PubKeySecp256k1": {
-      const pubkeyProto = PubKey.fromPartial({
-        key: fromBase64(pubkey.value),
-      });
-      return Any.fromPartial({
-        typeUrl: "/cosmos.crypto.secp256k1.PubKey",
-        value: Uint8Array.from(PubKey.encode(pubkeyProto).finish()),
-      });
-    }
-    default:
-      throw new Error(`Pubkey type ${pubkey.type} not recognized`);
+export function encodePubkey(pubkey: Pubkey): Any {
+  if (isSecp256k1Pubkey(pubkey)) {
+    const pubkeyProto = PubKey.fromPartial({
+      key: fromBase64(pubkey.value),
+    });
+    return Any.fromPartial({
+      typeUrl: "/cosmos.crypto.secp256k1.PubKey",
+      value: Uint8Array.from(PubKey.encode(pubkeyProto).finish()),
+    });
+  } else if (isMultisigThresholdPubkey(pubkey)) {
+    const pubkeyProto = LegacyAminoPubKey.fromPartial({
+      threshold: Uint53.fromString(pubkey.value.threshold).toNumber(),
+      publicKeys: pubkey.value.pubkeys.map(encodePubkey),
+    });
+    return Any.fromPartial({
+      typeUrl: "/cosmos.crypto.multisig.LegacyAminoPubKey",
+      value: Uint8Array.from(LegacyAminoPubKey.encode(pubkeyProto).finish()),
+    });
+  } else {
+    throw new Error(`Pubkey type ${pubkey.type} not recognized`);
   }
 }
 
-export function decodePubkey(pubkey?: Any | null): AminoPubKey | null {
+export function decodePubkey(pubkey?: Any | null): SinglePubkey | null {
   if (!pubkey || !pubkey.value) {
     return null;
   }