ACTRT2 (Arp-T2) is a testis-specific actin-related protein that serves as a structural component of the sperm head perinuclear theca, the cytoskeletal calyx that resists high ionic strength and detergent extraction, where it is a major acidic constituent expressed late in spermatid differentiation PMID:12243744. Within the subacrosomal region of developing spermatids, ACTRT2 assembles into a multimeric perinuclear theca complex with ACTRT1, ACTL7A, ACTL9, and ACTRT3 that anchors the developing acrosome to the sperm nucleus during spermiogenesis; loss of complex integrity produces acrosomal detachment [PMID:35616329, PMID:41668650]. In human spermatozoa it localizes to the post-acrosomal region and middle piece, and its expression is reduced in obesity-associated asthenozoospermia PMID:25293813. Beyond its structural role, ACTRT2 protects spermatogonia against ferroptosis: its loss drives intracellular iron overload, mitochondrial damage, and a shift in ferroptosis regulators (upregulation of ACSL4 and ALOX15 with downregulation of SLC7A11 and GPX4) that sensitizes cells to busulfan-induced death PMID:40811009.
Recorded for reference. The AIGR evaluation found this grounding is coarse (collapses to general parents) and can contradict the narrative — do not import these GO ids directly; re-ground from the narrative + PMIDs.
| Year | Confidence | Finding | PMIDs | Journal |
|---|---|---|---|---|
| 2002 | Medium | ACTRT2 (Arp-T2) is a novel actin-related protein that localizes specifically to the cytoskeletal calyx of the mammalian sperm head (perinuclear theca), is expressed specifically in the testis late in spermatid differentiation, and is a major acidic component of the calyx structure characterized by resistance to high ionic strength and detergents. | PMID:12243744 | Experimental cell research |
| 2022 | High | ACTRT2 interacts with ACTRT1, ACTL7A, and ACTL9 to form a multimeric complex that localizes to the subacrosomal region of spermatids and is required for anchoring the developing acrosome to the nucleus; this complex mediates the acrosome-nucleus connection during spermiogenesis. | PMID:35616329 | Development (Cambridge, England) |
| 2014 | Medium | ACTRT2 localizes to the post-acrosomal region and middle piece of human spermatozoa, and its expression is decreased in obesity-associated asthenozoospermia. | PMID:25293813 | Andrology |
| 2025 | Medium | ACTRT2 deficiency in spermatogonia increases vulnerability to ferroptosis: loss of ACTRT2 leads to intracellular iron overload (upregulation of SLC11A2, IREB2, TFRC), mitochondrial damage, upregulation of pro-ferroptotic ACSL4 and ALOX15, and downregulation of anti-ferroptotic SLC7A11 and GPX4, resulting in increased cell death upon busulfan treatment. | PMID:40811009 | Molecular human reproduction |
| 2026 | Medium | ACTRT2 physically interacts with ACTRT3 (ARPM1/ACTRT3) as part of a perinuclear theca protein complex in spermatids, as demonstrated by co-immunoprecipitation in the context of ACTRT3 characterization. | PMID:41668650 | Development (Cambridge, England) |
| 2025 | Low | ACTRT2 interacts with ACTRT1 and ACTL7A (and ARPM1/ACTRT3) as part of the perinuclear theca cytoskeletal complex, corroborating its role as a structural component linking acrosome to nucleus. | PMID:bio_10.1101_2025.03.27.645694 | bioRxiv |