A2PE hydrolyses to A2E

Stable Identifier
Reaction [transition]
Homo sapiens
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The outer segment of photoreceptor cells is shed every 10-14 days to be completely replaced. The shed material is phagocytosed and transferred to the retinal pigment epithelium (RPE). Diretinoid-pyridinium-phosphatidylethanolamine (A2PE) can be hydrolysed to diretinoid-pyridinium-ethanolamine (A2E), a prominent constituent of lipofuscin (the material deposited in retinal tissue which accumulates over time and is implicated in macular degeneration). Evidence suggests this happens before transfer to RPE cells as part of the phagocytosed outer segment. A2E has been detected in outer segments (Ben-Shabat et al. 2002) and an N-acyl-phosphatidylethanolamine-hydrolyzing phospholipase D (NAPEPLD) activity detected in rat, mouse and human proteins (Okamoto et al. 2004, Ueda et al. 2005, Wang et al. 2006). This activity has been shown to hydrolyse A2PE to A2E in bovine outer segments before phagocytosis and transfer to RPE cells, suggesting A2PE is hydrolysed to A2E in photoreceptor outer segment membranes (Sparrow et al. 2003, Salvador & Giusto 1998).
Literature References
PubMed ID Title Journal Year
14634025 Molecular characterization of a phospholipase D generating anandamide and its congeners

Morishita, J, Okamoto, Y, Tonai, T, Ueda, N, Tsuboi, K

J. Biol. Chem. 2004
14611934 A2E, a byproduct of the visual cycle

Jang, YP, Krane, S, Nakanishi, K, Cai, B, Fishkin, N, Sparrow, JR, Itagaki, Y, Zhou, J

Vision Res. 2003
9778132 Characterization of phospholipase D activity in bovine photoreceptor membranes

Giusto, NM, Salvador, GA

Lipids 1998
15949819 N-acylphosphatidylethanolamine-hydrolyzing phospholipase D: a novel enzyme of the beta-lactamase fold family releasing anandamide and other N-acylethanolamines

Morishita, J, Okamoto, Y, Ueda, N

Life Sci. 2005
11756445 Biosynthetic studies of A2E, a major fluorophore of retinal pigment epithelial lipofuscin

Vollmer, HR, Nakanishi, K, Fishkin, N, Parish, CA, Sparrow, JR, Ben-Shabat, S, Itagaki, Y

J. Biol. Chem. 2002
16527816 Functional analysis of the purified anandamide-generating phospholipase D as a member of the metallo-beta-lactamase family

Morishita, J, Okamoto, Y, Wang, J, Ueda, N, Tsuboi, K, Miyatake, A

J. Biol. Chem. 2006
Catalyst Activity

N-acylphosphatidylethanolamine-specific phospholipase D activity of NAPEPLD [photoreceptor outer segment membrane]

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