You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Protein", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Dexamethasone", ...], "Protein" : ["BRCA-1", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A 46-amino acid segment in phosphodiesterase-5 GAF-B domain provides for high vardenafil potency over sildenafil and tadalafil and is involved in phosphodiesterase-5 dimerization.
Phosphodiesterase-5 (PDE5) contains a catalytic domain (C domain) that hydrolyzes cGMP and a regulatory domain (R domain) that contains two mammalian cGMP-binding phosphodiesterase, Anabaena adenylyl cyclases, Escherichia coli FhlAs (GAFs) (A and B) and a phosphorylation site for cyclic nucleotide-dependent protein kinases (cNPKs). Binding of cGMP to GAF-A increases cNPK phosphorylation of PDE5 and improves catalytic site affinity for cGMP or inhibitors. GAF-B contributes to dimerization of PDE5, inhibition of cGMP binding to GAF-A, and sequestration of the phosphorylation site. To probe potential PDE5 R domain effects on catalytic site affinity for certain inhibitors, four N-terminal truncation mutants were generated: PDE5Delta1-321 contained GAF-B domain, C domain, and the sequence between GAF-A and -B; PDE5Delta1-419 contained GAF-B and C domain; PDE5Delta1-465 contained the C domain and the C-terminal portion of GAF-B; and PDE5Delta1-534 contained only C domain. Truncated proteins with a complete GAF-B were dimers, but those lacking the N-terminal 46 amino acids of GAF-B were monomers, indicating that these residues are vital for GAF-B-mediated PDE5 dimerization. K(m) values of the mutants for cGMP were similar to that of full-length PDE5. All PDE5 constructs had similar affinities for 3-isobutyl-1-methylxanthine, sildenafil, tadalafil, and UK-122764, but mutants containing a complete GAF-B had 7- to 18-fold higher affinity for vardenafil-based compounds compared with those lacking a complete GAF-B. This indicated that the N-terminal 46 amino acids in GAF-B are required for high vardenafil potency. This is the first evidence that PDE5 R domain, and GAF-B in particular, influences affinity and selectivity of the catalytic site for certain classes of inhibitors.
{"Chemical": ["UK-122764", "vardenafil", "amino acids", "amino acid", "cyclic nucleotide", "N", "3-isobutyl-1-methylxanthine", "cGMP", "sildenafil", "tadalafil", "adenylyl", "C"], "Protein": ["phosphodiesterase-5", "PDE5Delta1-321", "GAF-B", "PDE5Delta1-465", "GAF-B and C domain", "cNPK", "Anabaena adenylyl cyclases", "GAF-B domain", "GAF-A", "GAF-A and -B", "(GAFs) (A and B)", "cNPKs", "Escherichia coli FhlAs", "PDE5 R domain", "PDE5Delta1-419", "PDE5Delta1-534", "cyclic nucleotide-dependent protein kinases", "mammalian cGMP-binding phosphodiesterase", "PDE5", "Phosphodiesterase-5"]}