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: ["RNA", "CellLine", "Protein", "DNA", "CellType"].

Please return the output as a JSON object of the format: {"DNA" : ["TAL1", ...], "RNA": ["mRNAs", ...], "CellLine": ["T cells", ...], "CellType": ["monocytes", ...], "Protein": ["IL-2", ...]}. 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:

Human erythroid 5-aminolevulinate synthase: promoter analysis and identification of an iron-responsive element in the mRNA. 5-Aminolevulinate synthase (ALAS) catalyzes the first step of the heme biosynthetic pathway. cDNA clones for the human erythroid ALAS isozyme were isolated from a fetal liver library. It can be deduced that the erythroid ALAS precursor protein has a molecular weight of 64. 6 kd, and is similar in size to the previously isolated human housekeeping ALAS precursor of molecular weight 70. 6 kd. The mature mitochondrial forms of the erythroid and housekeeping ALAS isozymes are predicted to have molecular weights of 59. 5 kd and 64. 6 kd, respectively. The two isozymes show little amino acid identity in their N-terminal signal sequences but have considerable sequence identity in the C-terminal two-thirds of their proteins. An analysis of the immediate promoter of the human erythroid ALAS gene revealed several putative erythroid-specific cis-acting elements including both a GATA-1 and an NF-E2 binding site. An iron-responsive element (IRE) motif has been identified in the 5'-untranslated region of the human erythroid ALAS mRNA, but is not present in the housekeeping ALAS mRNA. Gel retardation experiments established that this IRE motif formed a protein-RNA complex with cytosolic extracts from human K562 cells and this binding was strongly competed with IRE transcripts from ferritin or transferrin receptor mRNAs. A transcript of the ALAS IRE, mutated in the conserved loop of the IRE, did not readily form this protein-RNA complex. These results suggest that the IRE motif in the ALAS mRNA is functional and imply that translation of the mRNA is controlled by cellular iron availability during erythropoiesis.
{"CellLine": ["extracts from human"], "CellType": [], "DNA": ["fetal liver library", "human erythroid ALAS gene", "ALAS IRE", "NF - E2 binding site", "promoter", "immediate promoter", "cDNA clones", "iron - responsive element", "IRE", "GATA - 1", "erythroid - specific cis - acting elements"], "Protein": ["5 - Aminolevulinate synthase (ALAS)", "ALAS", "protein  -", "Human erythroid 5 - aminolevulinate synthase", "C - terminal two - thirds", "human erythroid ALAS isozyme", "isozymes", "N - terminal signal sequences", "heme", "5 - Aminolevulinate synthase", "housekeeping ALAS isozymes", "erythroid ALAS precursor protein", "human housekeeping ALAS precursor"], "RNA": ["competed with", "iron - responsive element (IRE) motif", "mRNA", "human erythroid ALAS mRNA", "housekeeping ALAS mRNA", "transcripts from ferritin or transferrin", "ALAS mRNA", "IRE motif"]}