Table 1.

GO overrepresentation analysis reveals enrichment of specific categories of molecular function among developmentally upregulated (top) and downregulated (bottom) genes

GO term (molecular function)	p value	Found/total
Upregulated genes
Transporter activity	0.004	101/1454
Channel or pore class transporter activity	0.003	34/386
Ion transporter activity	8 × 10−6	62/655
Ion channel activity	2 × 10−4	34/330
Voltage-gated ion channel activity	2 × 10−6	25/163
Voltage-gated potassium channel activity	6 × 10−5	16/98
Cation channel activity	3 × 10−5	29/237
Potassium channel activity	2 × 10−5	20/130
Metal ion transporter activity	0.003	11/77
Cation transporter activity	4 × 10−6	53/518
Potassium ion binding	5 × 10−4	14/95
Magnesium ion binding	5 × 10−5	32/281
Catalytic activity	5 × 10−5	311/4879
Oxidoreductase activity, acting on NADH or NADPH	0.007	9/64
Kinase activity	0.007	65/890
Inositol or phosphatidylinositol phosphatase activity	0.008	6/33
Phosphoinositide 5-phosphatase activity	0.001	3/5
Acetylglucosaminyltransferase activity	0.004	5/21
Downregulated genes
Protein binding	1 × 10−4	207/3733
RNA binding	6 × 10−5	44/533
Calmodulin binding	0.002	12/105
Cytoskeletal protein binding	5 × 10−5	31/325
Structural constituent of ribosome	2 × 10−4	23/228
Oxidoreductase activity, acting on paired donors	4 × 10−4	4/9
Calcium channel regulator activity	0.002	4/13
Voltage-gated calcium channel activity	0.009	4/19
Voltage-gated sodium channel activity	0.001	4/12

Hierarchical relationship of GO terms is denoted by indentation. p values were calculated using the hypergeometric probability distribution, which computes the probability of finding a given GO term in the list of differentially expressed genes (found), given the total number of genes on the Affymetrix GeneChip annotated with that term (total). All terms with p < 0.01 are shown.