This is a receptor for VIP as well as PACAP-38 and -27, the activity of this receptor is mediated by G proteins which activate adenylyl cyclase. Can be coupled to phospholipase C.
J. Clin. Immunol. 16, 21-30 (1996)[PubMed:8926282]
An immunoregulatory role for vasoactive intestinal peptide (VIP) is suggested by the high concentrations in subsets of neurons supplying lymphoid organs and by the capacity of VIP to affect T lymphocyte functions. The Tsup-1 line of human T lymphoblastoma cells expresses both type I and type II G protein-coupled VIP receptors (Rs), as shown by detection of the encoding mRNAs with reverse transcription-polymerase chain reaction analyses. Northern blot quantification of the relative amounts of mRNA encoding the two VIPRs in Tsup-1 cells indicated that type II predominates over type I, as it does in human blood CD4+ T cells. Tsup-1 cells bound 125I-VIP to 8.95 x 10(4) high-affinity sites/cell (Kd = 6.0 nM) and 7.45 x 10(5) low-affinity sites/cell (Kd = 210 nM). VIP increased [cAMP]i in Tsup-1 cells (EC50 = 14.4 nM) and stimulated a rapid and transient increase in [Ca2+]i (EC50 = 30 nM). Functional coupling of G proteins to type II VIPRs was suggested by the change in binding of 125I-VIP to Tsup-1 cell membranes from two sites with Kd values of 3.8 and 109 nM to one site of Kd 30 nM by GTP-gamma-S and the suppression by pertussis toxin of increases in [Ca2+]i evoked by VIP. The VIP antagonists, VIP4-28 and (4-Cl-D-Phe6-Leu17) VIP, inhibited 125I-VIP binding by type II VIPRs, as well as VIP-elicited increases in [Ca2+]i and [cAMP]i. Type II VIPRs thus are the major transducers of VIP signals to a subset of human T cells.
Combining with an extracellular signal and transmitting the signal across the membrane by activating an associated G-protein; promotes the exchange of GDP for GTP on the alpha subunit of a heterotrimeric G-protein complex.
We have cloned and sequenced a cDNA isolated from a human SUP-T1 lymphoblast cell line library. It encoded a 457 amino acids protein having 87% identity with the rat PACAP type II, VIP2 receptor. Chinese hamster ovary (CHO) cells stably transfected with cloned cDNA expressed a specific binding of 125I[Acetyl-His1]PACAP-27. This binding was inhibited by GTP, and by the peptides helodermin, VIP, PACAP-27 and PACAP-38 that also stimulated adenylate cyclase activity. The order of potency was PACAP-38 > VIP > or = helodermin > or = PACAP-27. Comparison of the results in two cell lines expressing different receptor densities suggested that helodermin and PACAP-38 had a higher intrinsic activity than VIP and PACAP-27.
The major immunoregulatory effects of vasoactive intestinal peptide (VIP) are mediated by structurally distinct types I (VIPR1) and II (VIPR2) G protein-associated receptors on some T cells, B cells, and macrophages. Identification of the separate immunologic activities of each type of VIPR has been complicated by the usual expression of only VIPR2 or of VIPR1 and VIPR2 together by most human T cells obtainable in sufficient number for functional analyses. The results of reverse-transcription PCR, Western blot, and [125I]VIP-binding studies have established that HuT 78 cultured human lymphoma T cells bear a mean of 75,000 VIPR1s per cell with a mean Kd of 3.3 nM, which transduce mean maximal increases in intracellular concentration of cAMP of 2.1-fold (ED50 = 72 nM), but no VIPR2s. HuT 78 T cells, in contrast to T cells that express VIPR2, did not respond to VIP by chemotaxis through micropore filters without or with a top layer of basement membrane-like Matrigel. Matrix metalloproteinase (MMP)-dependent in situ cleavage of [3H]type IV human collagen in the layer of Matrigel by HuT 78 T cells also was not stimulated by VIP. In contrast, IL-4 and TNF-alpha both stimulated HuT 78 T cell chemotaxis and in situ MMP activity at respective optimal concentrations ranging from 3 x 10(-10) M to 3 x 10(-9) M and 10(-10) M to 3 x 10(-10) M. VIP inhibited significantly HuT 78 T cell chemotaxis through Matrigel in response to both IL-4 and TNF-alpha, as a result of suppression of both chemotactic mobility, assessed by migration through micropore filters without Matrigel, and in situ MMP activity. The transduction of opposite effects of VIP on T cell migration through a model basement membrane by VIPR1 and VIPR2 suggests that the net chemotactic response of most T cells to VIP is determined by the VIPR2/VIPR1 ratio and that the predominant expression of VIPR1 would stabilize T cell populations in lymphoid follicles and tissue infiltrates.
The cellular process in which a signal is conveyed to trigger a change in the activity or state of a cell. Signal transduction begins with reception of a signal (e.g. a ligand binding to a receptor or receptor activation by a stimulus such as light), or for signal transduction in the absence of ligand, signal-withdrawal or the activity of a constitutively active receptor. Signal transduction ends with regulation of a downstream cellular process, e.g. regulation of transcription or regulation of a metabolic process. Signal transduction covers signaling from receptors located on the surface of the cell and signaling via molecules located within the cell. For signaling between cells, signal transduction is restricted to events at and within the receiving cell.
We have cloned and sequenced a cDNA isolated from a human SUP-T1 lymphoblast cell line library. It encoded a 457 amino acids protein having 87% identity with the rat PACAP type II, VIP2 receptor. Chinese hamster ovary (CHO) cells stably transfected with cloned cDNA expressed a specific binding of 125I[Acetyl-His1]PACAP-27. This binding was inhibited by GTP, and by the peptides helodermin, VIP, PACAP-27 and PACAP-38 that also stimulated adenylate cyclase activity. The order of potency was PACAP-38 > VIP > or = helodermin > or = PACAP-27. Comparison of the results in two cell lines expressing different receptor densities suggested that helodermin and PACAP-38 had a higher intrinsic activity than VIP and PACAP-27.
Receptors which transduce extracellular signals across the cell membrane. At the external side they receive a ligand (a photon in case of opsins), and at the cytosolic side they activate a guanine nucleotide-binding (G) protein. These receptors are hydrophobic proteins that cross the membrane seven times.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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