Paralemmin 2 is a shared, alternatively-spliced regulator of axon initial segments and paranodal junctions in oligodendrocytes
Nervous system function depends on highly specialized axonal membrane domains. For example, axon initial segments (AIS), nodes of Ranvier, and paranodal junctions are essential for action potential initia-tion and saltatory conduction. These domains use shared molecular machinery converging on the master scaffolding protein AnkyrinG (AnkG). Using endogenous AnkG-TurboID proximity proteomics, we…
Nervous system function relies on specialized membrane regions, such as axon initial segments, nodes of Ranvier, and paranodal junctions. These critical areas rely on the scaffolding protein AnkyrinG for action potential initiation and saltatory conduction. Researchers have now discovered a new member, Paralemmin 2, which shares these essential membrane parts in both neurons and oligodendrocytes.
Palm2 is transiently found in neurons' AIS and nodes during development, but becomes a permanent fixture at paranodes throughout an organism's life. This suggests that cell type-specific splicing of a lipid-modified domain is responsible for Palm2's interaction with AnkyrinG. Interestingly, mice lacking oligodendroglial Palm2 still form normal paranodes during growth, but aging mice experience impaired paranode integrity due to the loss of both paranodal AnkG and Neurofascin-155.
This research highlights Palm2 as a lipid raft-associated regulator of axonal and oligodendroglial membrane domains, supporting the idea that specialized protein variants are common in shaping the unique membrane architectures of different cell types.
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