Two splice variants of Golgi-microtubule-associated protein of 210 kDa (GMAP-210) differ in their binding to the cis-Golgi network.
GMAP-210 (Golgi-microtubule-associated protein of 210 kDa) is a peripheral Golgi protein that interacts with the minus end of microtubules through its C-terminus and with cis-Golgi network membranes through its N-terminus; it participates in the maintenance of the structural integrity of the Golgi apparatus [Infante, Ramos-Morales, Fedriani, Bornens and Rios (1999) J. Cell Biol. 145, 83--98]. We report here the cloning of a new isoform of GMAP-210 that lacks amino acid residues 105--196. On the basis of the analysis of the gmap-210 genomic sequence, we propose that the small isoform, GMAP-200, arises from alternative splicing of exon 4 of the primary transcript. Overexpression of GMAP-200 induces perturbations in both the Golgi apparatus and the microtubule network that are similar to those previously reported for GMAP-210 overexpression. We show that both isoforms are able to oligomerize under overexpression conditions. Analysis in vitro and in vivo, with the green fluorescent protein as a marker, reveals that the binding of the N-terminal domain of GMAP-200 to the cis-Golgi network membranes is lower than that of the N-terminal domain of GMAP-210. Implications for the regulation of interaction between the cis-Golgi network and microtubules are discussed.
Ramos-Morales
F
F
Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain.
Vime
C
C
Bornens
M
M
Fedriani
C
C
Rios
R M
RM
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D004247:DNA / Q000032:analysis; D005091:Exons / Q000235:genetics; D017353:Gene Deletion; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins
D003598:Cytoskeletal Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; C109331:TRIP11 protein, human; D004247:DNA