| Category | Specific finding | Key quantitative data (if any) | Source (first author year) | Publication date (month/year if known) | URL/DOI |
|---|---|---|---|---|---|
| Identity | **CAT2 (YML042W)** in *S. cerevisiae* encodes **Cat2p**, the major carnitine acetyltransferase/carnitine O-acetyltransferase in yeast; literature distinguishes it from the mitochondrial carnitine carrier gene (**YOR100C/CAC/CRC1**). (pqac-00000005, pqac-00000006, pqac-00000008) | Major CAT enzyme in yeast | van Roermund 1999; Freitag 2024 | Nov 1999; Jan 2024 | https://doi.org/10.1093/emboj/18.21.5843 ; https://doi.org/10.1177/25152564241264254 |
| Reaction | Cat2p catalyzes **reversible transfer of acetyl groups between acetyl-CoA and L-carnitine**, i.e. acetyl-CoA + carnitine ⇄ CoA + acetylcarnitine; in the peroxisome it forms acetylcarnitine, and in mitochondria the reverse reaction regenerates acetyl-CoA for the TCA cycle. (pqac-00000016, pqac-00000017, pqac-00000018) | Reversible acetyl transfer; no kinetic constants retrieved in context | Swiegers 2001; van Roermund 1999 | May 2001; Nov 1999 | https://doi.org/10.1002/yea.712 ; https://doi.org/10.1093/emboj/18.21.5843 |
| Localization | Cat2p is **dually localized to peroxisomes and mitochondria**; review and thesis evidence describe dual targeting mediated by N-terminal mitochondrial targeting information plus a C-terminal peroxisomal targeting signal, with two ATG codons contributing to alternative targeting. (pqac-00000000, pqac-00000005, pqac-00000008) | Dual organellar localization | van Roermund 1999; Franken 2009; Freitag 2024 | Nov 1999; 2009; Jan 2024 | https://doi.org/10.1093/emboj/18.21.5843 ; https://doi.org/10.1177/25152564241264254 |
| Pathway role | Cat2p is central to the **carnitine shuttle** that moves acetyl units from peroxisomes to mitochondria when acetyl-CoA itself cannot cross membranes; this pathway complements the glyoxylate-cycle route for acetyl-unit utilization. (pqac-00000005, pqac-00000009, pqac-00000010) | Functions in one of two parallel acetyl-unit transport routes | van Roermund 1999; Swiegers 2001 | Nov 1999; May 2001 | https://doi.org/10.1093/emboj/18.21.5843 ; https://doi.org/10.1002/yea.712 |
| Genetics & phenotypes | **cat2Δ single mutants** can grow similarly to wild type on tested carbon sources, but **Δcit2 Δcat2** double mutants fail on oleate/non-fermentable carbon sources, showing redundancy between Cat2-mediated shuttle and the glyoxylate-cycle pathway. (pqac-00000002, pqac-00000004, pqac-00000017) | Double-mutant synthetic growth defect/loss on oleate and related conditions | van Roermund 1999; Swiegers 2001 | Nov 1999; May 2001 | https://doi.org/10.1093/emboj/18.21.5843 ; https://doi.org/10.1002/yea.712 |
| Genetics & phenotypes | All three yeast carnitine acetyltransferases—**CAT2, YAT1, YAT2**—are required for a fully functional carnitine shuttle in a **cit2-disrupted** background, and they do **not cross-complement**, implying distinct subcellular roles. (pqac-00000000, pqac-00000003) | YAT2 contributes ~50% of total CAT activity on ethanol; no cross-complementation | Swiegers 2001; Franken 2009 | May 2001; 2009 | https://doi.org/10.1002/yea.712 |
| Quantitative activity | Cat2p provides the **majority of total carnitine acetyltransferase activity** in yeast. Reported contributions vary with growth condition: **~95% in oleate-grown cells**, **>99% in galactose-grown cells**, and **~95% overall dominance** in review/thesis summaries. (pqac-00000001, pqac-00000005, pqac-00000010) | ~95% (oleate); >99% (galactose) | van Roermund 1999; Swiegers 2001 | Nov 1999; May 2001 | https://doi.org/10.1093/emboj/18.21.5843 ; https://doi.org/10.1002/yea.712 |
| Quantitative activity | Fractionation/enzyme-assay excerpts report bimodal Cat activity in *S. cerevisiae* organelle fractions, with **82.2 nmol/min/mg** in the peroxisomal peak and **122.6 nmol/min/mg** in the mitochondrial peak; the same source states CAT2 contributes about **95%** of total activity in oleate-grown cells. (pqac-00000013, pqac-00000020) | 82.2 vs 122.6 nmol/min/mg; ~95% of total activity | Strijbis et al. unknown year excerpt | Unknown | URL not available in gathered context |
| Recent 2023-2024 developments | A 2024 review places Cat2 among **dually targeted mitochondria/peroxisome proteins** and notes that organelle tethering can influence whether such proteins remain mitochondrial or proceed to peroxisomes, affecting Cat2 “to some extent.” (pqac-00000011, pqac-00000023) | No Cat2-specific numeric values reported | Freitag 2024 | Jan 2024 | https://doi.org/10.1177/25152564241264254 |
| Recent 2023-2024 developments | In acetate-grown cells, **Cat2 with an N-terminal fluorescent tag showed punctate/peroxisomal localization**, whereas **C-terminal tagging disrupted the PTS1-dependent punctate pattern**, yielding predominant mitochondrial localization; this supports dual targeting and sensitivity of Cat2 localization to tag placement. (pqac-00000014, pqac-00000022) | Proteomics/transcriptomics used 3 biological replicates; analysis thresholds ≥1.5 or ≤0.66 fold, p=0.05, but no Cat2-specific fold-change given | Kosir 2024 | Mar 2024 | https://doi.org/10.1101/2024.03.20.585854 |
| Applications & engineering | Cat2 has been repurposed in **metabolic engineering**: anchoring **Cat2 to the peroxisome surface** was used to channel acetyl units from peroxisomal β-oxidation toward the cytosolic acetyl-CoA pool for ophiobolin biosynthesis; authors explicitly exploit the **bidirectionality** of Cat2 catalysis. (pqac-00000028) | Surface-localized Cat2 strain (**Yoph20**) reached **5.1 g/L** ophiobolin F after 72 h fed-batch whole-cell transformation; other reported titers include **178 mg/L**, **649.6 mg/L**, and **742.3 mg/L** OphF in intermediate strains/conditions | Zhang 2024 | May 2024 | https://doi.org/10.1186/s12934-024-02406-0 |


*Table: This table summarizes verified findings on *S. cerevisiae* CAT2/Cat2p, covering identity, biochemical function, localization, pathway context, genetics, quantitative activity, and recent 2023-2024 developments. It is useful as a compact evidence map linking classic yeast genetics with current organelle biology and metabolic engineering work.*