diff --git a/proxy/grpcproxy/kv.go b/proxy/grpcproxy/kv.go
index c68f1b1c5..09b95458b 100644
--- a/proxy/grpcproxy/kv.go
+++ b/proxy/grpcproxy/kv.go
@@ -99,28 +99,13 @@ func (p *kvProxy) txnToCache(reqs []*pb.RequestOp, resps []*pb.ResponseOp) {
 }
 
 func (p *kvProxy) Txn(ctx context.Context, r *pb.TxnRequest) (*pb.TxnResponse, error) {
-	txn := p.kv.Txn(ctx)
-	cmps := make([]clientv3.Cmp, len(r.Compare))
-	thenops := make([]clientv3.Op, len(r.Success))
-	elseops := make([]clientv3.Op, len(r.Failure))
-
-	for i := range r.Compare {
-		cmps[i] = (clientv3.Cmp)(*r.Compare[i])
-	}
-
-	for i := range r.Success {
-		thenops[i] = requestOpToOp(r.Success[i])
-	}
-
-	for i := range r.Failure {
-		elseops[i] = requestOpToOp(r.Failure[i])
-	}
-
-	resp, err := txn.If(cmps...).Then(thenops...).Else(elseops...).Commit()
-
+	op := TxnRequestToOp(r)
+	opResp, err := p.kv.Do(ctx, op)
 	if err != nil {
 		return nil, err
 	}
+	resp := opResp.Txn()
+
 	// txn may claim an outdated key is updated; be safe and invalidate
 	for _, cmp := range r.Compare {
 		p.cache.Invalidate(cmp.Key, cmp.RangeEnd)
@@ -167,6 +152,10 @@ func requestOpToOp(union *pb.RequestOp) clientv3.Op {
 		if tv.RequestDeleteRange != nil {
 			return DelRequestToOp(tv.RequestDeleteRange)
 		}
+	case *pb.RequestOp_RequestTxn:
+		if tv.RequestTxn != nil {
+			return TxnRequestToOp(tv.RequestTxn)
+		}
 	}
 	panic("unknown request")
 }
@@ -219,3 +208,19 @@ func DelRequestToOp(r *pb.DeleteRangeRequest) clientv3.Op {
 	}
 	return clientv3.OpDelete(string(r.Key), opts...)
 }
+
+func TxnRequestToOp(r *pb.TxnRequest) clientv3.Op {
+	cmps := make([]clientv3.Cmp, len(r.Compare))
+	thenops := make([]clientv3.Op, len(r.Success))
+	elseops := make([]clientv3.Op, len(r.Failure))
+	for i := range r.Compare {
+		cmps[i] = (clientv3.Cmp)(*r.Compare[i])
+	}
+	for i := range r.Success {
+		thenops[i] = requestOpToOp(r.Success[i])
+	}
+	for i := range r.Failure {
+		elseops[i] = requestOpToOp(r.Failure[i])
+	}
+	return clientv3.OpTxn(cmps, thenops, elseops)
+}