Fox T, Fitzgibbon M J, Fleming M A, Hsiao H M, Brummel C L, Su M S
Vertex Pharmaceuticals Incorporated, 130 Waverly Street, Cambridge, MA 02139-4242, USA.
FEBS Lett. 1999 Nov 19;461(3):323-8. doi: 10.1016/s0014-5793(99)01488-x.
Activated p38gamma MAP kinase exhibited significant basal ATPase activity in the absence of a kinase substrate, and addition of a phosphoacceptor substrate increased k(cat)/K(m)20-fold. AMP-PCP was competitive with ATP binding and non-competitive with phosphoacceptor substrate binding. The nucleotide binding site affinity label 5'-(p-fluorosulfonylbenzoyl)adenosine (FSBA) bound stoichiometrically at Lys-56 in the ATP site of both unphosphorylated and activated p38gamma. AMP-PCP only protected the activated enzyme from FSBA inactivation, implying that AMP-PCP does not bind unphosphorylated p38gamma. Basal ATPase activities were also observed for activated p38alpha, ERK2 and JNK3 suggesting that the enzymatic mechanism may be similar for all classes of MAP kinases.
活化的p38γ丝裂原活化蛋白激酶（MAP激酶）在没有激酶底物的情况下表现出显著的基础ATP酶活性，添加磷酸受体底物可使催化常数（k(cat)）与米氏常数（K(m)）的比值增加20倍。腺苷-5'-三磷酸（AMP-PCP）与ATP结合具有竞争性，与磷酸受体底物结合不具有竞争性。核苷酸结合位点亲和标记物5'-（对氟磺酰苯甲酰）腺苷（FSBA）在未磷酸化和活化的p38γ的ATP位点的赖氨酸-56处按化学计量结合。AMP-PCP仅保护活化的酶免受FSBA失活，这意味着AMP-PCP不与未磷酸化的p38γ结合。活化的p38α、细胞外信号调节激酶2（ERK2）和应激活化蛋白激酶3（JNK3）也观察到基础ATP酶活性，这表明所有类型的MAP激酶的酶促机制可能相似。
