Krishnan Kannan, Moens Pierre D J
Centre for Bioactive Discovery in Health and Ageing, School of Science and Technology, University of New England, McClymont Bldg, Armidale, NSW, 2351, Australia.
Biophys Rev. 2009 Jul;1(2):71-81. doi: 10.1007/s12551-009-0010-y. Epub 2009 Jun 4.
Profilins are small actin-binding proteins found in eukaryotes and certain viruses that are involved in cell development, cytokinesis, membrane trafficking, and cell motility. Originally identified as an actin sequestering/binding protein, profilin has been involved in actin polymerization dynamics. It catalyzes the exchange of ADP/ATP in actin and increases the rate of polymerization. Profilins also interact with polyphosphoinositides (PPI) and proline-rich domains containing proteins. Through its interaction with PPIs, profilin has been linked to signaling pathways between the cell membrane and the cytoskeleton, while its role in membrane trafficking has been associated with its interaction with proline-rich domain-containing proteins. Depending on the organism, profilin is present in a various number of isoforms. Four isoforms of profilin have been reported in higher organisms, while only one or two isoforms are expressed in single-cell organisms. The affinity of these isoforms for their ligands varies between isoforms and should therefore modulate their functions. However, the significance and the functions of the different isoforms are not yet fully understood. The structures of many profilin isoforms have been solved both in the presence and the absence of actin and poly-L-proline. These structural studies will greatly improve our understanding of the differences and similarities between the different profilins. Structural stability studies of different profilins are also shedding some light on our understanding of the profilin/ligand interactions. Profilin is a multifaceted protein for which a dramatic increase in potential functions has been found in recent years; as such, it has been implicated in a variety of physiological and pathological processes.
丝切蛋白是在真核生物和某些病毒中发现的小肌动蛋白结合蛋白，参与细胞发育、胞质分裂、膜运输和细胞运动。丝切蛋白最初被鉴定为一种肌动蛋白隔离/结合蛋白，参与肌动蛋白聚合动力学。它催化肌动蛋白中ADP/ATP的交换，并提高聚合速率。丝切蛋白还与多磷酸肌醇（PPI）和富含脯氨酸结构域的蛋白质相互作用。通过与PPI的相互作用，丝切蛋白与细胞膜和细胞骨架之间的信号通路相关联，而其在膜运输中的作用与其与富含脯氨酸结构域的蛋白质的相互作用有关。根据生物体的不同，丝切蛋白以多种异构体形式存在。在高等生物中已报道有四种丝切蛋白异构体，而在单细胞生物中仅表达一种或两种异构体。这些异构体对其配体的亲和力因异构体而异，因此应该会调节它们的功能。然而，不同异构体的意义和功能尚未完全了解。许多丝切蛋白异构体的结构在有和没有肌动蛋白及聚-L-脯氨酸的情况下都已得到解析。这些结构研究将极大地增进我们对不同丝切蛋白之间差异和相似性的理解。不同丝切蛋白的结构稳定性研究也为我们理解丝切蛋白/配体相互作用提供了一些线索。丝切蛋白是一种多面蛋白，近年来发现其潜在功能有显著增加；因此，它与多种生理和病理过程有关。
