Table 1.
Human ALDH proteins.
| ALDH | Subcellular location | Preferred aldehyde substrate | Additional functions and characteristics |
|---|---|---|---|
| ALDH1A1 | Cytosol | Retinal | Ester hydrolysis; binds androgen, cholesterol, thyroid, daunorubicin, and flavopiridol; corneal and lens crystallin; oxidizes DOPAL, acetaldehyde |
| ALDH1A2 | Cytosol | Retinal | High affinity for LPO-derived aldehydes |
| ALDH1A3 | Cytosol | Retinal | High affinity for LPO-derived aldehydes |
| ALDH1B1 | Mitochondria | Acetaldehyde | May protect the cornea from UV-light |
| ALDH1L1 | Cytosol | 10-Formyltetrahydrofolate | Binds acetaminophen |
| ALDH1L2 | Unknown | Unknown | Induced by the anti-inflammatory agent indomethacin |
| ALDH2 | Mitochondria | Acetaldehyde | Ester hydrolysis; nitroglycerin bioactivation, oxidizes LPO-derived aldehydes; binds acetaminophen; oxidizes DOPAL and DOPEGAL |
| ALDH3A1 | Cytosol, nucleus* | Aromatic, aliphatic aldehydes | Ester hydrolysis; scavenges ROS; UV-filter; corneal crystallin; oxidizes LPO-derived aldehydes; regulation of cell-cycle; inducted by PAHs |
| ALDH3A2 | Microsomes, peroxisomes ‡ | Fatty aldehydes | Insulin regulates gene expression |
| ALDH3B1 | Cytosol § | Unknown | Oxidizes LPO-derived aldehydes |
| ALDH3B2 | Unknown | Unknown | Unknown |
| ALDH4A1 | Mitochondria | Glutamate γ-semialdehyde | Ester hydrolysis; may mitigate oxidative stress |
| ALDH5A1 | Mitochondria | Succinate semialdehyde | May be involved in neurotransmission efficiency |
| ALDH6A1 | Mitochondria | Malonate semialdehyde | Esterase activity; only known human CoA-dependent ALDH |
| ALDH7A1 | Cytosol, nucleus, mitochondria¶ | α-Aminoadipic semialdehyde | Closely related to plant osmoregulatory protein; may regulate cell cycle |
| ALDH8A1 | Cytosol | Retinal | Oxidizes LPO-derived aldehydes and acetaldehyde |
| ALDH9A1 | Cytosol | γ-Aminobutyraldehyde | Oxidizes betaine, acetaldehyde and DOPAL; involved in carnitine biosysnthesis; esterase activity |
| ALDH16A1 | Unknown | Unknown | Unknown |
| ALDH18A1 | Mitochondria | Glutamic γ-semialdehyde | Unknown |
*
While predominantly cytosolic, ALDH3A1 is also found in the nucleus.
‡
A variant of ALDH3A2, FALDHv, is believed to be localized to the peroxisomes.
§
Marchitti SA, Vasiliou V. unpublished data.
¶
Brocker C, Cantore M, Pappa A, et al. unpublished data.