A ras-related protein is phosphorylated and translocated by agonists that increase cAMP levels in human platelets.
نویسندگان
چکیده
The antigenicity of platelet proteins was assayed against various monoclonal antibodies (mAbs) that recognize specific epitopes of the ras-encoded p21 protein. mAb M90, which detects the region of p21 protein within amino acids 107-130 and inhibits its GTP-binding activity, strongly reacted with a 22-kDa protein present in the particulate fraction of human platelets. Other mAbs against ras-encoded proteins, including Y13-259, which efficiently detects ras proteins from a variety of organisms, did not recognize the platelet 22-kDa protein. Transfer of the platelet 22-kDa protein to nitrocellulose paper showed that the protein binds [alpha-32P]GTP. Moreover, preincubation of the transferred protein with mAb M90 drastically reduced its GTP-binding activity. Treatment of platelets with iloprost, a prostacyclin analog, caused (i) a time-dependent increase of a 24-kDa protein that is recognized by mAb M90 in particulate and cytosolic fractions and (ii) the gradual decrease of the 22-kDa protein from the particulate fraction. When platelets were labeled with 32P and then treated with iloprost, the 24-kDa protein was found to be phosphorylated. The 32P-labeled 24-kDa protein was specifically immunoprecipitated by mAb M90. These results suggest that appearance of the 24-kDa protein results from phosphorylation of the 22-kDa protein, which shifts its mobility to a higher molecular mass area.
منابع مشابه
بررسی اثر افزایش cAMP بر فسفوریلاسیون پروتئین BAD در ردهی سلولی لوسمی لنفوبلاستیک حاد پیش سازB- (NALM-6) تیمارشده با دوکسوروبیسین
Kashiri M1, Safa M2, Kazemi A3 1Dept. of Hematology, Allied Medical School, Tehran University of Medical Sciences, Tehran, Iran 2Cellular and Molecular Research Center, Dept. of Hematology and Blood Banking, Faculty of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran 3Dept. of Hematology & Blood Banking, School of Allied Medicine, Iran University of Medical Sciences, Tehran, I...
متن کاملCyclic nucleotides modulate store-mediated calcium entry through the activation of protein-tyrosine phosphatases and altered actin polymerization in human platelets.
Agonists elevate the cytosolic calcium concentration in human platelets via a receptor-operated mechanism, involving both Ca(2+) release from intracellular stores and subsequent Ca(2+) entry, which can be inhibited by platelet inhibitors, such as prostaglandin E(1) and nitroprusside which elevate cAMP and cGMP, respectively. In the present study we investigated the mechanisms by which cAMP and ...
متن کاملEffect of Adenosine Agonists on the Proliferation and Differentiation of Chick Embryo Fibroblasts in Three Dimensional Reconstituted Tissue Constructs
Previous studies indicate that organ fibroblasts play an important role in wound healing, collagen production, remodeling processes and pathogenesis of progressive heart, lung, renal and hepatic fibrotic diseases. Several studies suggest a possible inhibitory role for adenosine in the regulation of fibroblast proliferation. The effect of adenosine A2 agonists on proliferation and differentiatio...
متن کاملPhosphorylation results in activation of a cAMP phosphodiesterase in human platelets.
Agents such as prostaglandins E1 and I2 which elevate cAMP levels in platelets also increase cAMP phosphodiesterase activity. Since much of the cAMP phosphodiesterase activity in human platelets is due to the cGMP-inhibited isozyme (Macphee, C. H., Harrison, S. A., and Beavo, J. A. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 6600-6663), we examined the regulation of this isozyme by prostaglandin...
متن کاملInduction of Human Embryonic Stem Cells into neuronal differentiation by increasing cyclic Adenosine Mono Phosphate
Introduction: To evaluate the cAMP -mediated IBMX (3-IsoButyle -1-Methyl Xanthin) and db-cAMP (dibutyryl cAMP) effects on differentiation of human Embryonic Stem Cells (hESCs) into nerve cells were the objectives of this study. Methods: We have used Royan H1 hESC- derived embryoid bodies with four treatment groups: six days treatment with IBMX (5×10 -4M) and db-cAMP (10 -9M) (referred to as...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 86 9 شماره
صفحات -
تاریخ انتشار 1989