Differential phosphorylation of microtubule proteins by ATP and GTP

Abstract

Purified brain microtubule protein is phosphorylated by endogenous protein kinase activities in the presence of [gamma-32P] ATP or [gamma-32P] GTP. Here we show that certain microtubule-associated proteins are phosphorylated differently by GTP or ATP as direct phosphoryl donors, suggesting the presence of distinct kinase activities, with different specificities, associated with microtubule protein.

Depletion of casein kinase II by antisense oligonucleotide prevents neuritogenesis in neuroblastoma cells.

“…Furthermore, immunohistochemical studies show that CKII is more concentrated in neurons than in glial cells (Iimoto et al, 1989;Girault et al, 1990), suggesting a potentially important role for this enzyme in specific neuronal functions. In particular, one of the proposed roles for casein kinase II in developing neurons has been the promotion of neuritogenesis through the phosphorylation of several cytoskeletal proteins including microtubule-associated protein MAPlB (Diaz-Nido et al, 1988, 1990a, 1991, 1992Serrano et al, 1989) and the neuronal-specific OM tubulin (Serrano et al, 1987;Dfaz-Nido et al, 1990a,b).…”

Differentiation of neuroblastoma cells correlates with an altered splicing pattern of tau RNA

“…Phosphate labclling was performed for 20 h with 1 mCi/ml a2P (Amersham) as previously described [20]. [ Oligonucleotides Rl and Ct or Rl and R2 were mixed with total cDNA, For PCR amplification the cDNA products were mixed with 1 ,uM of the oligonuclcotidcs used.…”

“…N2A neuroblastoma cells were cultured in the presence (undifferentiated cells) or in the absence (differentiated cells) of serum [20] and fixed with cold methanol for immunofluorescence analyses. The analyses were carried out using different antibodies againt tau.…”

“…During neuroblastoma cell differentiation a net increase in the amount of microtubule polymer has been extensively described [18,20,21]. This increase has been correlated with an increase in the phosphorylation of beta tubulin subunit and MAP,B [EL211, but other factors, like tau factor, could be involved in the change of polymer amount.…”

Changes in microtubule-associated protein IB during development of the nervous system

“…Alkaline phosphatase treatment of young rat brain supernatant can generate the band pattern observed in the adult, suggesting that maturation is associated with dephosphorylation of MAP1B [23]. In neuronal outgrowth in PC12 cells "241, and in neuroblastoma cells [25], MAP 1 B becomes phosphorylated.…”