Goldberg-Shprintzen syndrome (GOSHS) is a rare clinical disorder characterized 
by central and enteric nervous system defects. This syndrome is caused by 
inactivating mutations in the Kinesin Binding Protein (KBP) gene, which encodes 
a protein of which the precise function is largely unclear. We show that KBP 
expression is up-regulated during neuronal development in mouse cortical 
neurons. Moreover, KBP-depleted PC12 cells were defective in nerve growth 
factor-induced differentiation and neurite outgrowth, suggesting that KBP is 
required for cell differentiation and neurite development. To identify KBP 
interacting proteins, we performed a yeast two-hybrid screen and found that KBP 
binds almost exclusively to microtubule associated or related proteins, 
specifically SCG10 and several kinesins. We confirmed these results by 
validating KBP interaction with one of these proteins: SCG10, a microtubule 
destabilizing protein. Zebrafish studies further demonstrated an epistatic 
interaction between KBP and SCG10 in vivo. To investigate the possibility of 
direct interaction between KBP and microtubules, we undertook co-localization 
and in vitro binding assays, but found no evidence of direct binding. Thus, our 
data indicate that KBP is involved in neuronal differentiation and that the 
central and enteric nervous system defects seen in GOSHS are likely caused by 
microtubule-related defects.