Receptor occupancy and adenylate cyclase activation in AR 4-2J rat pancreatic acinar cell membranes by analogs of pituitary adenylate cyclase-activating peptides amino-terminally shortened or modified at position 1, 2, 3, 20, or 21.
Receptor occupancy and adenylate cyclase activation in AR 4-2J rat pancreatic acinar cell membranes by analogs of pituitary adenylate cyclase-activating peptides amino-terminally shortened or modified at position 1, 2, 3, 20, or 21.
复制标题
在 1、2、3、20 或 21 位氨基末端缩短或修饰的垂体腺苷酸环化酶激活肽类似物对 AR 4-2J 大鼠胰腺腺泡细胞膜中的受体占据和腺苷酸环化酶激活。
作者：
P. Robberecht;P. Gourlet;P. de Neef;M. Woussen;M. Vandermeers;A. Vandermeers;J. Christophe
在AR 4- 2 J大鼠胰腺腺泡细胞膜中，两种垂体腺苷酸环化酶激活肽（PACAP）的受体PACAP-27（PACAP的短版本）和PACAP-38 [长版本，具有羧基末端（残基28-38）延伸]可以细分为（a）A型受体，具有高亲和力（Kd，0.3-0.5 nM），以及（B）B型受体，对PACAP-38具有高亲和力（Kd，0.3 nM），但对PACAP-27具有低亲和力（Kd，20 nM）。47种PACAP-27和PACAP-38类似物中激动剂/拮抗剂活性的决定因素（1、2、3、20和21位单取代或双取代）或氨基末端缩短通过（a）优先用[125 I-N-乙酰基-His 1]PACAP-27标记的PACAP-A受体的占有率，以及均用125 I-PACAP-38标记的PACAP-A和-B受体的占有率，和（B）腺苷酸环化酶的活化或抑制。对于PACAP-A受体的识别，去质子化的His 1是PACAP-27而不是PACAP-38的主要决定因素; 125 I-PACAP-27的Kd在pH 6.0和7.5之间在37 ℃下降低2.4倍，在15 ℃下降低3.6倍，而[N-乙酰基-His 1]PACAP-27的IC 50受影响较小，PACAP（2-27），PACAP（2-38），PACAP（1-38）不依赖于pH。此外，与腺苷酸环化酶偶联的PACAP-A受体对PACAP-38衍生物比对PACAP-27衍生物更敏感;例如，[D-Phe 2]PACAP-38是比[D-Phe 2]PACAP-27（Ki，350 nM）更有效的拮抗剂（Ki，5 nM），而PACAP（6-38）是比PACAP（6-27）（Ki，300 nM）更有效的拮抗剂（Ki，7 nM）。PACAP-B受体除了对PACAP-38显示出高亲和力外，对氨基末端缩短的PACAP-38片段显示出相对高的亲和力，而对PACAP-27和PACAP-27片段显示出差的亲和力。
In AR 4-2J rat pancreatic acinar cell membranes, receptors for the two pituitary adenylate cyclase-activating peptides (PACAP) PACAP-27 (the short version of PACAP) and PACAP-38 [the long version, with a carboxyl-terminal (residues 28-38) extension] can be subdivided into (a) type A receptors, with high affinity (Kd, 0.3-0.5 nM) for both PACAP-27 and PACAP-38, and (b) type B receptors, with high affinity for PACAP-38 (Kd, 0.3 nM) but low affinity for PACAP-27 (Kd, 20 nM). Determinants of agonist/antagonist activity in 47 PACAP-27 and PACAP-38 analogs (mono- or disubstituted in positions 1, 2, 3, 20, and 21) or amino-terminally shortened were tested by (a) the occupancy of PACAP-A receptors, preferentially labeled with [125I-N-acetyl-His1]PACAP-27, and that of PACAP-A and -B receptors, both labeled with 125I-PACAP-38, and (b) the resulting activation or inhibition of adenylate cyclase. For PACAP-A receptor recognition, deprotonated His1 was a major determinant for PACAP-27 but not PACAP-38; the Kd of 125I-PACAP-27 decreased 2.4-fold at 37 degrees between pH 6.0 and 7.5 and 3.6-fold at 15 degrees, whereas the IC50 of [N-acetyl-His1]PACAP-27 was less affected and that of PACAP(2-27), PACAP(2-38), and PACAP(1-38) was pH independent. In addition, PACAP-A receptors coupled to adenylate cyclase were much more sensitive to PACAP-38 derivatives than to PACAP-27 derivatives; for instance, [D-Phe2]PACAP-38 was a more potent antagonist (Ki, 5 nM) than [D-Phe2]PACAP-27 (Ki, 350 nM), and PACAP(6-38) was a more potent antagonist (Ki, 7 nM) than PACAP(6-27) (Ki, 300 nM). PACAP-B receptors, apart from showing high affinity for PACAP-38, displayed relatively high affinity for amino-terminally shortened PACAP-38 fragments and poor affinity for PACAP-27 and PACAP-27 fragments.