Alternative titles; symbols
HGNC Approved Gene Symbol: TRG-CCC1-1
Cytogenetic location: 1p36.13 Genomic coordinates (GRCh38): 1:16,545,939-16,546,009 (from NCBI)
McBride et al. (1989) assigned a glycine tRNA(CCC) gene (TRG1) to human chromosome 1 (1pter-p34) on the basis of Southern analysis of a panel of hybrid cell DNAs. They also assigned a cloned DNA fragment encompassing a glycine tRNA gene (tRNA-GCC) and pseudogene to human chromosome 16 by the same method.
There are about 1,300 tRNA genes in the haploid human genome (Hatlen and Attardi, 1971) encoding 60 to 90 tRNA isoacceptors (Lin and Agris, 1980). The studies by McBride et al. (1989) as well as studies by others (see, e.g., 180620, 189930, 189920, 180640, 189880) indicated that tRNA genes and pseudogenes are dispersed on at least 7 human chromosomes and suggested that these sequences would probably be found on most if not all human chromosomes. McBride et al. (1989) described short, 8-12 nucleotide, direct terminal repeats flanking many of the dispersed tRNA genes. This finding, combined with the dispersion of tRNA genes, suggests that many of these genes may have arisen by an RNA-mediated retroposition mechanism. There may have been selection for reiteration of genes encoding isoaccepting tRNAs, since a single mutation in a single-copy tRNA gene could be devastating. Moreover, even a mutation in the anticodon of a single tRNA gene might not be crucial if competition was provided by the normal 'wildtype' tRNA isoacceptor produced by multiple copies of the normal tRNA gene still present in the genome. Dispersion of multiple copies of each tRNA gene could provide diversity of 5-prime-flanking sequences, which are known to modulate the expression of some human tRNA genes. Tissue-specific or differentiation-specific expression of tRNA isoacceptors might be provided for by this mechanism. The recombination and unequal crossingover that can occur with tandem tRNA sequences can result in homogenization of the sequences with disastrous consequences.
Hatlen, L., Attardi, G. Proportion of the HeLa cell genome complementary to transfer RNA and 5S RNA. J. Molec. Biol. 56: 535-553, 1971. [PubMed: 4929578] [Full Text: https://doi.org/10.1016/0022-2836(71)90400-1]
Lin, V. K., Agris, P. F. Alterations in tRNA isoaccepting species during erythroid differentiation of the Friend leukemia cell. Nucleic Acids Res. 8: 3467-3480, 1980. [PubMed: 6904970] [Full Text: https://doi.org/10.1093/nar/8.15.3467]
McBride, O. W., Pirtle, I. L., Pirtle, R. M. Localization of three DNA segments encompassing tRNA genes to human chromosomes 1, 5, and 16: proposed mechanism and significance of tRNA gene dispersion. Genomics 5: 561-573, 1989. [PubMed: 2613239] [Full Text: https://doi.org/10.1016/0888-7543(89)90024-4]