diff --git a/src/mol-repr/structure/visual/util/common.ts b/src/mol-repr/structure/visual/util/common.ts
index 1e2f479d22e546a668aab603854caf7841db563f..cd0e2271a17f32e5821ebca489f0f935eb15c4a8 100644
--- a/src/mol-repr/structure/visual/util/common.ts
+++ b/src/mol-repr/structure/visual/util/common.ts
@@ -11,7 +11,7 @@ import { OrderedSet, SortedArray } from 'mol-data/int';
 import { EmptyLoci, Loci } from 'mol-model/loci';
 
 /** Return a Loci for the elements of a whole residue the elementIndex belongs to. */
-export function getResidueLoci(structure: Structure, unit: Unit, elementIndex: ElementIndex): Loci {
+export function getResidueLoci(structure: Structure, unit: Unit.Atomic, elementIndex: ElementIndex): Loci {
     const { elements, model } = unit
     if (OrderedSet.indexOf(elements, elementIndex) !== -1) {
         const { index, offsets } = model.atomicHierarchy.residueAtomSegments
diff --git a/src/mol-repr/structure/visual/util/polymer.ts b/src/mol-repr/structure/visual/util/polymer.ts
index 71b987a3ea8b5ac3954524d393e59875b55b5733..bf0f536b8c15cbbd1f4f98788507fd9fa6807e4e 100644
--- a/src/mol-repr/structure/visual/util/polymer.ts
+++ b/src/mol-repr/structure/visual/util/polymer.ts
@@ -72,12 +72,25 @@ export function getPolymerElementLoci(pickingId: PickingId, structureGroup: Stru
     if (id === objectId) {
         const { structure, group } = structureGroup
         const unit = group.units[instanceId]
-        return getResidueLoci(structure, unit, unit.polymerElements[groupId])
+        if (Unit.isAtomic(unit)) {
+            return getResidueLoci(structure, unit, unit.polymerElements[groupId])
+        } else {
+            const { elements } = unit
+            const elementIndex = unit.polymerElements[groupId]
+            const unitIndex = OrderedSet.indexOf(elements, elementIndex) as StructureElement.UnitIndex | -1
+            if (unitIndex !== -1) {
+                const indices = OrderedSet.ofSingleton(unitIndex)
+                return StructureElement.Loci(structure, [{ unit, indices }])
+            }
+        }
     }
     return EmptyLoci
 }
 
-/** Mark a polymer element (e.g. part of a cartoon trace) when all its residue's elements are in a loci. */
+/**
+ * Mark a polymer element (e.g. part of a cartoon trace)
+ * - for atomic units mark only when all its residue's elements are in a loci
+ */
 export function eachPolymerElement(loci: Loci, structureGroup: StructureGroup, apply: (interval: Interval) => boolean) {
     let changed = false
     if (!StructureElement.isLoci(loci)) return false
@@ -90,19 +103,32 @@ export function eachPolymerElement(loci: Loci, structureGroup: StructureGroup, a
     for (const e of loci.elements) {
         const unitIdx = group.unitIndexMap.get(e.unit.id)
         if (unitIdx !== undefined) {
-            // TODO optimized implementation for intervals
-            OrderedSet.forEach(e.indices, v => {
-                const rI = index[elements[v]]
-                const unitIndexMin = OrderedSet.findPredecessorIndex(elements, offsets[rI])
-                const unitIndexMax = OrderedSet.findPredecessorIndex(elements, offsets[rI + 1] - 1)
-                const unitIndexInterval = Interval.ofRange(unitIndexMin, unitIndexMax)
-                if (!OrderedSet.isSubset(e.indices, unitIndexInterval)) return
-                const eI = traceElementIndex[rI]
-                const idx = OrderedSet.indexOf(e.unit.polymerElements, eI)
-                if (idx !== -1) {
-                    if (apply(Interval.ofSingleton(unitIdx * groupCount + idx))) changed = true
+            if (Unit.isAtomic(e.unit)) {
+                // TODO optimized implementation for intervals
+                OrderedSet.forEach(e.indices, v => {
+                    const rI = index[elements[v]]
+                    const unitIndexMin = OrderedSet.findPredecessorIndex(elements, offsets[rI])
+                    const unitIndexMax = OrderedSet.findPredecessorIndex(elements, offsets[rI + 1] - 1)
+                    const unitIndexInterval = Interval.ofRange(unitIndexMin, unitIndexMax)
+                    if (!OrderedSet.isSubset(e.indices, unitIndexInterval)) return
+                    const eI = traceElementIndex[rI]
+                    const idx = OrderedSet.indexOf(e.unit.polymerElements, eI)
+                    if (idx !== -1) {
+                        if (apply(Interval.ofSingleton(unitIdx * groupCount + idx))) changed = true
+                    }
+                })
+            } else {
+                if (Interval.is(e.indices)) {
+                    const start = unitIdx * groupCount + Interval.start(e.indices);
+                    const end = unitIdx * groupCount + Interval.end(e.indices);
+                    if (apply(Interval.ofBounds(start, end))) changed = true
+                } else {
+                    for (let i = 0, _i = e.indices.length; i < _i; i++) {
+                        const idx = unitIdx * groupCount + e.indices[i];
+                        if (apply(Interval.ofSingleton(idx))) changed = true
+                    }
                 }
-            })
+            }
         }
     }
     return changed