| Gene Symbol | TOP3B |
|---|---|
| Entrez Gene | 8940 |
| Alt Symbol | TOP3B1 |
| Species | Human |
| Gene Type | protein-coding |
| Description | topoisomerase (DNA) III beta |
| Other Description | DNA topoisomerase 3-beta-1|DNA topoisomerase III beta-1|topoisomerase III beta |
| Swissprots | A0M8Q3 O95985 Q9BUP5 |
| Accessions | BAA20009 EAW59487 EAW59488 EAW59489 EAW59490 EAW59491 O95985 AF017146 AAD01614 AF053082 AAD15791 AF125216 AAD29670 AK096695 BAG53351 AK290997 BAF83686 AK304681 BAG65452 AK304709 BAG65474 AL833505 BC002432 AAH02432 BQ270362 CR456596 CAG30482 CU013196 CAK54627 CU013484 CAK54926 DA025312 XM_005261811 XP_005261868 XM_005261813 XP_005261870 XM_006724349 XP_006724412 XM_006724350 XP_006724413 XM_011530482 XP_011528784 XM_011530483 XP_011528785 XM_011530484 XP_011528786 XR_244395 XR_937945 XR_937946 NM_001282112 NP_001269041 NM_001282113 NP_001269042 NM_003935 NP_003926 |
| Function | Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand than undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone (By similarity). Possesses negatively supercoiled DNA relaxing activity. {ECO:0000250}. |
| Tissue Specificity | Isoform 1 is found in testis, heart and skeletal muscle. A 4 kb transcript which probably represents isoform 2 is found in thymus, kidney and pancreas. {ECO:0000269|PubMed:9927731}. |
| Top Pathways | Homologous recombination, Fanconi anemia pathway |