diff --git a/Code/GraphMol/CMakeLists.txt b/Code/GraphMol/CMakeLists.txt
index 3c567b66e..0e4b608f3 100644
--- a/Code/GraphMol/CMakeLists.txt
+++ b/Code/GraphMol/CMakeLists.txt
@@ -7,7 +7,7 @@ rdkit_library(GraphMol
               MolDiscriminators.cpp ConjugHybrid.cpp AddHs.cpp
               Matrices.cpp Chirality.cpp RingInfo.cpp Conformer.cpp
               Renumber.cpp AdjustQuery.cpp Resonance.cpp StereoGroup.cpp
-              new_canon.cpp SubstanceGroup.cpp FindStereo.cpp
+              new_canon.cpp SubstanceGroup.cpp FindStereo.cpp MonomerInfo.cpp
               SHARED
               LINK_LIBRARIES RDGeometryLib RDGeneral  )
 target_compile_definitions(GraphMol PRIVATE RDKIT_GRAPHMOL_BUILD)
diff --git a/Code/GraphMol/MonomerInfo.cpp b/Code/GraphMol/MonomerInfo.cpp
new file mode 100644
index 000000000..817d5b0f6
--- /dev/null
+++ b/Code/GraphMol/MonomerInfo.cpp
@@ -0,0 +1,21 @@
+//
+//  Copyright (C) 2021 Greg Landrum and other RDKit contributors
+//
+//   @@ All Rights Reserved @@
+//  This file is part of the RDKit.
+//  The contents are covered by the terms of the BSD license
+//  which is included in the file license.txt, found at the root
+//  of the RDKit source tree.
+//
+#include <iostream>
+#include "MonomerInfo.h"
+
+using namespace RDKit;
+
+//! allows AtomPDBResidueInfo objects to be dumped to streams
+std::ostream &operator<<(std::ostream &target, const AtomPDBResidueInfo &apri) {
+  target << apri.getSerialNumber() << " " << apri.getName() << " "
+         << apri.getResidueName() << " " << apri.getChainId() << " "
+         << apri.getResidueNumber();
+  return target;
+}
diff --git a/Code/GraphMol/MonomerInfo.h b/Code/GraphMol/MonomerInfo.h
index af9b5dadd..f373448ce 100644
--- a/Code/GraphMol/MonomerInfo.h
+++ b/Code/GraphMol/MonomerInfo.h
@@ -1,5 +1,5 @@
 //
-//  Copyright (C) 2013 Greg Landrum
+//  Copyright (C) 2013-2021 Greg Landrum and other RDKit contributors
 //
 //   @@ All Rights Reserved @@
 //  This file is part of the RDKit.
@@ -13,8 +13,8 @@
 
 */
 #include <RDGeneral/export.h>
-#ifndef _RD_MONOMERINFO_H
-#define _RD_MONOMERINFO_H
+#ifndef RD_MONOMERINFO_H
+#define RD_MONOMERINFO_H
 
 #include <string>
 #include <utility>
diff --git a/Code/GraphMol/catch_graphmol.cpp b/Code/GraphMol/catch_graphmol.cpp
index e9fe61465..0376bf220 100644
--- a/Code/GraphMol/catch_graphmol.cpp
+++ b/Code/GraphMol/catch_graphmol.cpp
@@ -14,7 +14,9 @@
 #include <GraphMol/new_canon.h>
 #include <GraphMol/RDKitQueries.h>
 #include <GraphMol/Chirality.h>
+#include <GraphMol/MonomerInfo.h>
 #include <GraphMol/FileParsers/FileParsers.h>
+#include <GraphMol/FileParsers/SequenceParsers.h>
 #include <GraphMol/SmilesParse/SmilesParse.h>
 #include <GraphMol/SmilesParse/SmilesWrite.h>
 #include <GraphMol/SmilesParse/SmartsWrite.h>
@@ -2434,4 +2436,27 @@ TEST_CASE("KekulizeIfPossible") {
       }
     }
   }
+}
+
+TEST_CASE("Github #4535: operator<< for AtomPDBResidue", "[PDB]") {
+  SECTION("basics") {
+    bool sanitize = true;
+    int flavor = 0;
+    std::unique_ptr<RWMol> mol(SequenceToMol("KY", sanitize, flavor));
+    REQUIRE(mol);
+    REQUIRE(mol->getAtomWithIdx(0)->getMonomerInfo());
+    auto res = static_cast<AtomPDBResidueInfo *>(
+        mol->getAtomWithIdx(0)->getMonomerInfo());
+    REQUIRE(res);
+    std::stringstream oss;
+    oss << *res << std::endl;
+    res = static_cast<AtomPDBResidueInfo *>(
+        mol->getAtomWithIdx(mol->getNumAtoms() - 1)->getMonomerInfo());
+    REQUIRE(res);
+    oss << *res << std::endl;
+    auto tgt = R"FOO(1  N   LYS A 1
+22  OXT TYR A 2
+)FOO";
+    CHECK(oss.str() == tgt);
+  }
 }
\ No newline at end of file