Autonomous functions for the Sec14p/spectrin-repeat region of Kalirin

Authors

Martin R. Schiller, University of Nevada, Las VegasFollow
Francesco Ferraro, University of Connecticut Health Center
Yanping Wang, University of Connecticut Health CenterFollow
Xin-ming Ma, University of Connecticut Health Center
Clifton E. McPherson, University of Connecticut Health Center
Jacqueline A. Sobota, University of Connecticut Health Center
Noraisha I. Schiller, University of Connecticut Health CenterFollow
Richard E. Mains, University of Connecticut Health CenterFollow
Betty A. Eipper, University of Connecticut Health CenterFollow

Document Type

Article

Publication Date

8-15-2008

Publication Title

Experimental Cell Research

Volume

14

Issue

14

First page number:

2674

Last page number:

2691

Abstract

Kalirin is a GDP/GTP exchange factor (GEF) for Rho proteins that modulates the actin cytoskeleton in neurons. Alternative splicing generates Delta-isoforms, which encode the RhoGEF domain, but lack the N-terminal Sec14p domain and first 4 spectrin-like repeats of the full-length isoforms. Splicing has functional consequences, with Kal7 but not DeltaKal7 causing formation of dendritic spines. Cells lacking endogenous Kalirin were used to explore differences between these splice variants. Expression of DeltaKal7 in this system induces extensive lamellipodial sheets, while expression of Kal7 induces formation of adherent compact, round cells with abundant cortical actin. Based on in vitro and cell-based assays, Kal7 and DeltaKal7 are equally active GEFs, suggesting that other domains are involved in controlling cell morphology. Catalytically inactive Kal7 and a Kalirin fragment which includes only Sec14p and spectrin-like domains retain the ability to produce compact, round cells and fractionate as high molecular weight complexes. Separating the Sec14p domain from the spectrin-like repeats eliminates the ability of Kal7 to cause this response. The isolated Sec14p domain binds PI(3,5)P2 and PI3P, but does not alter cell morphology. We conclude that the Sec14p and N-terminal spectrin-like domains of Kalirin play critical roles in distinguishing the actions of full-length and Delta-Kalirin proteins.

Keywords

Alternative Splicing; Amino acid sequence; Animals; Cell Shape; Cells; Cultured; Cells—Morphology; Cytoskeleton; Cytoskeleton/Metabolism; Endocytosis; G proteins; Genetic engineering; Guanine Nucleotide Exchange Factors/Chemistry; Guanine Nucleotide Exchange Factors/Metabolism; Kalirin 4; Mutant Proteins/Metabolism; Neurons; Neurons/Cytology; Neurons/Metabolism; Phenotype; Phosphatidylinositides; Protein binding; Proteins—Structure; Protein Structure; Quaternary; Protein Structure; Tertiary; Rats; Repetitive Sequences; Amino Acid; Structure-Activity Relationship; Transferrin; Transferrin Uptake

Disciplines

Life Sciences | Molecular and Cellular Neuroscience | Molecular Biology | Neuroscience and Neurobiology | Structural Biology

Language

English

Repository Citation

Schiller, M. R., Ferraro, F., Wang, Y., Ma, X., McPherson, C. E., Sobota, J. A., Schiller, N. I., Mains, R. E., Eipper, B. A. (2008). Autonomous functions for the Sec14p/spectrin-repeat region of Kalirin. Experimental Cell Research, 14(14), 2674-2691.
http://dx.doi.org/10.1016/j.yexcr.2008.05.011