Arp1

Arp1, short for actin-related protein 1, is a member of the actin-related protein family. In humans it is encoded by the ACTR1A gene; in other organisms, such as budding yeast, it is referred to as ARP1. Arp1 is a component of the dynactin complex, a multiprotein assembly that works with the dynein motor to mediate cargo transport along microtubules.

Arp1 forms a short, actin-like filament composed of Arp1 subunits that serves as the structural backbone of the dynactin complex. This filament is part of the dynactin structure and is associated with other subunits, including Arp11 and p150Glued, to provide a scaffold for dynein-mediated transport.

Functionally, Arp1 is not an enzyme; its primary role is architectural, supporting the recruitment and function of dynein within the dynactin complex and helping link dynein to vesicles, organelles, or other cargo. This supports minus-end–directed movement along microtubules, proper spindle orientation during mitosis, and various intracellular transport processes. Arp1 is predominantly cytoplasmic and is highly conserved across eukaryotes.

Dysfunction of dynactin components, including Arp1 in certain contexts, impairs dynein-based transport and can affect cell division and organelle positioning in model systems. Arp1 is one member of the larger ARP family, which includes several proteins that resemble actin but have specialized cellular roles.