STOP-like protein 21 is a novel member of the STOP family, revealing a Golgi localization of STOP proteins.
Neuronal microtubules are stabilized by two calmodulin-regulated microtubule-associated proteins, E-STOP and N-STOP, which when suppressed in mice induce severe synaptic and behavioral deficits. Here we show that mature neurons also contain a 21-kDa STOP-like protein, SL21, which shares calmodulin-binding and microtubule-stabilizing homology domains with STOP proteins. Accordingly, in different biochemical or cellular assays, SL21 has calmodulin binding and microtubule stabilizing activity. However, in cultured hippocampal neurons, SL21 antibodies principally stain the somatic Golgi and punctate Golgi material in neurites. In cycling cells, transfected SL21 decorates microtubules when expressed at high levels but is otherwise principally visible at the Golgi. The Golgi targeting of SL21 depends on the presence of cysteine residues located within the SL21 N-terminal domain, suggesting that Golgi targeting may require SL21 palmitoylation. Accordingly we find that SL21 is palmitoylated in vivo. N-STOP and E-STOP, which contain the Golgi targeting sequences present in SL21, also display distinct Golgi staining when expressed at low level in cycling cells. Thus neuronal proteins of the STOP family have the capacity to associate with Golgi material, which could be important for STOP synaptic functions.
Gory-Fauré
Sylvie
S
INSERM U366, Département Recherche et Dynamique Cellulaire/Cytosquelette, Commissariat à l'Energie Atomique Grenoble, 17 rue des Martyrs, 38054 Grenoble, cedex 9, France.
Windscheid
Vanessa
V
Bosc
Christophe
C
Peris
Leticia
L
Proietto
Dominique
D
Franck
Ronald
R
Denarier
Eric
E
Job
Didier
D
Andrieux
Annie
A
D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D006056:Golgi Apparatus / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000032:analysis* / Q000502:physiology; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D019308:Palmitic Acid / Q000378:metabolism; D013569:Synapses / Q000502:physiology
D002147:Calmodulin; C491894:MAP6 protein, human; D008869:Microtubule-Associated Proteins; C491893:Mtap6 protein, mouse; D019308:Palmitic Acid