First find out the IRI for "single-pass type IV membrane protein" in the subcellular location vocabulary used in uniprot. In this case "http://purl.uniprot.org/locations/9908".

As it subcellular location annotations are structured we need to find the exact placing in the topology.

?subcellularLocationAnnotation up:locatedIn  ?locatedIn .
?locatedIn                     up:topology   location:9908 .

Then you need to find the evidence for it. In UniProt RDF we have decided to add evidences using rdf reification and attributions.

[]            rdf:subject     ?locatedIn ;
              rdf:predicate   up:topology ;   
              rdf:object      location:9908 ;
              up:attribution  ?attribution .
?attribution  up:evidence     <http://purl.obolibrary.org/obo/ECO_0000305>

Taking this together we end up with the full query

PREFIX up:<http://purl.uniprot.org/core/> 
PREFIX rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX location:<http://purl.uniprot.org/locations/>
SELECT 
*
WHERE {
    ?entry     up:annotation/up:locatedIn  ?locatedIn .
    ?locatedIn up:topology    location:9908 .
    []         rdf:subject    ?locatedIn ;
               rdf:predicate  up:topology ;   
               rdf:object     location:9908 ;
               up:attribution/up:evidence  <http://purl.obolibrary.org/obo/ECO_0000305>.
}

While in this case location:9908 does not have more specific child terms it is useful to expand the query for those cases. e.g. if you where looking for "Single-pass membrane protein"

{
  BIND(location:9904 as ?location)
 } UNION {
  ?location rdfs:subClassOf location:9904 .
}
?locatedIn up:topology ?location.