Table 1.

Comparison of the COX-1 and COX-2 Isoforms.

Parameter	COX-1 Isoform	COX-2 Isoform
Style of expression	Constitutive	Inducible
Location	Chromosome 9	Chromosome 1
Relative size of active site	Smaller	Larger
Size of gene	22 kb	8.3 kb
TATA box	-	+
Size of mRNA	2.8 kb	4.5 kb
Molecular weight	70 kDa	72 kDa
Number of amino acids	576*	581†

^*602 amino acids have also been reported.¹²

^†604 amino acids have also been reported.¹²