InvivoPharm: Receptor binding assay CRO service
In Vitro Receptor Occupancy: Radioligand Binding Assay
Overview: A radioligand binding assay (competitive binding assay; receptor binding assay) gives the IC50 and Ki
value for receptor-drug interactions by measuring the ability of the (non-radioactive) test drug to compete with binding
of a radioactively-labeled drug for the targeted receptor in a homogenate.
Radioligand binding assay protocol (competition assay): Incubate a range of concentrations of the test drug together
with a radioligand for the receptor and a tissue homogenate or cell membrane homogenate containing the receptor.
After equilibrium has been reached, separate bound from free radioligand using a 36-well filtration apparatus. Count
radioactivity on the filters and plot results to obtain IC50 and Ki values for the test drug.
Testing: An IC50 and Ki value will be obtained for each test drug by measuring binding over the following suggested
concentrations: 0, 0.1, 0.3, 1, 3, 10, 30, 100, 300 and 1000 nM with triplicate determinations at each concentration and
three tubes to determine non-specific binding (= 36 assay tubes in total). Alternative drug concentrations can be
substituted upon request.
Approximate prices*:
Typical setup fee: $ 3,000 + radioligand and drug costs (where applicable)
$ 500 for each drug tested
*Please contact us to obtain a final quote and turn-around time. Setup fee includes determination of IC50 to a standard reference
compound.
Ordering and assay information: Receptor binding assays are conducted on a custom basis and without prior
validation by InvivoPharm. However, literature-standard protocols for the assay conditions, including radioligand,
receptor preparation, reference drug and drug for non-specific binding will be used and the protocol approved by the
client prior to starting work. In cases where an assay protocol does not give an adequate specific binding signal,
despite our best attempts at optimizing tissue concentration and incubation and wash times, the client will be charged
for material costs and setup fee only and unused test compounds returned to the client.
With the exception of a small supply of radioligands we keep in stock, a radioligand will normally be purchased from a
commercial vendor for each new radioligand binding assay. The cost of this will be included in the quotation price
and typically ranges between $ 500 - $1,000. If the client wishes to supply his own radioligand for the assay we
recommend that it be less than 6 - 12 months old to ensure accurate Ki values and a strong binding signal. Purity can
be checked by us by HPLC for an additional fee upon request.
Unless otherwise directed, the test compounds will be solubilized in DMSO to provide stock solutions for the
competitive binding assay. Quantity of the test drug needed for each receptor binding assay protocol is usually 2 - 3
mg.
Setup fee will be reduced or waived for larger contracts or additional contracts involving the same receptor assay.
Radioiodination service for peptides and protein binding assays
Example data:
Overview: A radioligand binding assay (competitive binding assay; receptor binding assay) gives the IC50 and Ki
value for receptor-drug interactions by measuring the ability of the (non-radioactive) test drug to compete with binding
of a radioactively-labeled drug for the targeted receptor in a homogenate.
Radioligand binding assay protocol (competition assay): Incubate a range of concentrations of the test drug together
with a radioligand for the receptor and a tissue homogenate or cell membrane homogenate containing the receptor.
After equilibrium has been reached, separate bound from free radioligand using a 36-well filtration apparatus. Count
radioactivity on the filters and plot results to obtain IC50 and Ki values for the test drug.
Testing: An IC50 and Ki value will be obtained for each test drug by measuring binding over the following suggested
concentrations: 0, 0.1, 0.3, 1, 3, 10, 30, 100, 300 and 1000 nM with triplicate determinations at each concentration and
three tubes to determine non-specific binding (= 36 assay tubes in total). Alternative drug concentrations can be
substituted upon request.
Approximate prices*:
Typical setup fee: $ 3,000 + radioligand and drug costs (where applicable)
$ 500 for each drug tested
*Please contact us to obtain a final quote and turn-around time. Setup fee includes determination of IC50 to a standard reference
compound.
Ordering and assay information: Receptor binding assays are conducted on a custom basis and without prior
validation by InvivoPharm. However, literature-standard protocols for the assay conditions, including radioligand,
receptor preparation, reference drug and drug for non-specific binding will be used and the protocol approved by the
client prior to starting work. In cases where an assay protocol does not give an adequate specific binding signal,
despite our best attempts at optimizing tissue concentration and incubation and wash times, the client will be charged
for material costs and setup fee only and unused test compounds returned to the client.
With the exception of a small supply of radioligands we keep in stock, a radioligand will normally be purchased from a
commercial vendor for each new radioligand binding assay. The cost of this will be included in the quotation price
and typically ranges between $ 500 - $1,000. If the client wishes to supply his own radioligand for the assay we
recommend that it be less than 6 - 12 months old to ensure accurate Ki values and a strong binding signal. Purity can
be checked by us by HPLC for an additional fee upon request.
Unless otherwise directed, the test compounds will be solubilized in DMSO to provide stock solutions for the
competitive binding assay. Quantity of the test drug needed for each receptor binding assay protocol is usually 2 - 3
mg.
Setup fee will be reduced or waived for larger contracts or additional contracts involving the same receptor assay.
Radioiodination service for peptides and protein binding assays
Example data:
Competitive radioligand binding assay. Displacement of
[3H]SR141716A binding to CB1 cannabinoid receptors in a mouse
brain homogenate by the cannabinoid agonists AM2233 and
WIN55212-2. Displacement curves are shown fit to a two-site
model with Ki values of 0.08 nM and 17 nM for AM2233 and 2 nM
and 43 nM for WIN55212-2.
[3H]SR141716A binding to CB1 cannabinoid receptors in a mouse
brain homogenate by the cannabinoid agonists AM2233 and
WIN55212-2. Displacement curves are shown fit to a two-site
model with Ki values of 0.08 nM and 17 nM for AM2233 and 2 nM
and 43 nM for WIN55212-2.
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