In humans, the rDNA is found along the nucleolar organiser regions, transcription of rDNA begins through a pre-ribosomal rRNA transcript, in some places it is referred to as 47s in others 45s, could anyone please clarify the difference between the two please?
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https://www.sciencedirect.com/topics/neuroscience/5-8s-ribosomal-rna
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Schematic representation of the human pre-rRNA processing pathways. The 47S pre-rRNA is converted to the 45S pre-rRNA following the initial cleavages at sites A′ in the 5′-ETS and at site 6, at the 3′-end of the mature 28S rRNA. The 45S is processed by three alternative pathways. In pathway A, the first cleavage in 45S takes place at site 1, generating the 41S pre-rRNA whose 5′-end corresponds to the 5′-end of the mature 18S rRNA. The 41S pre-rRNA is subsequently processed at site 2c, separating the 21S pre-rRNA, from the 32S pre-rRNA. The 3′-end of the 21S pre-rRNA is processed to generate the 18S rRNA. The 32S pre-rRNA is cleaved at site 4b, generating the 12S pre-rRNA and the 28S rRNA. Finally, the 3′-end of the 12S pre-rRNA is processed to generate the mature 5.8S rRNA. In pathway B, the first cleavage in 45S takes place at site 2c, generating the 34S and 32S pre-rRNAs. The 34S pre-rRNA is subsequently processed at site 1, generating the 21S pre-rRNA. The 3′-end of the 21S pre-rRNA is processed further to generate the 18S rRNA. The 32S pre-rRNA is processed as described for pathway A. In pathway C, the first cleavage in 45S takes place at site 4b, generating the 37S and the 28S rRNA. The 37S pre-rRNA is subsequently processed at site 1, generating the 26S pre-rRNA, which is subsequently cleaved at site 2 generating the 18S rRNA and the 17S pre-rRNA. This pre-rRNA is processed at site 3 generating the 12S pre-rRNA and the 3′-end of the 12S pre-rRNA is processed to generate the mature 5.8S rRNA. This representation of the pathways was based on the papers published by Bowman et al. (8) and Hadjiolova et al. (9). Open arrowheads indicate the subsequent cleavage sites. Dark arrowheads (P1–P7) underneath the 47S pre-rRNA indicate the positions of the oligonucleotide probes used in northern blot and the open arrows (PE1–PE3) indicate the oligonucleotide probes used in primer extensions analyses, respectively.
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