Chapter 23, Problem 22DAP

(a)

Summary Introduction

To determine: The mechanism that will increase or decrease insulin secretion by pancreatic $\beta$ cells with explanation.

Introduction:

Insulin is the peptide hormone that is secreted by pancreas; insulin is produced naturally in the body of an organism. Insulin is required by the cells to use glucose as energy source. Glyburide is an antidiabetic drug that has sulfonylureas that close relation with sulfonamide antibiotics.

Explanation of Solution

Pictorial representation:

Fig 1: represent the pathway of glyburide:

Fig.1: the pathway of glyburide

Explanation:

Treatment of diabetes with glyburide leads to the rapid secretion of insulin from the $\beta$ pancreatic cells. This will happen due to shut down of ATP- gated ${\text{K}}^{\text{+}}$ channel by glyburide. Insulin secretion will increase because of the depolarization of the membrane. The above fig 1 depicts the pathway of glyburide.

Conclusion

Conclusion:

Glyburide will increase the secretion of insulin by shutting down the ATP-gated ${\text{K}}^{\text{+}}$ channel.

(b)

Summary Introduction

To determine: The treatment process with glyburide that will reduce the symptoms of type 2 diabetes.

Introduction:

Glyburide is an antidiabetic drug that has sulfonylureas that has close relation with sulfonamide antibiotics. Type 2 diabetes is a severe case of diabetes that can be reversed by changing diet and lifestyle. To treat type 2 diabetes insulin is taken as injections..

Explanation of Solution

Explanation:

Glyburide drug will reduce the symptoms of type 2 diabetes because diabetes is a disease, which is cause due to the improper level of insulin. Glyburide will increase the secretion of insulin, and increased insulin level will reduces the symptoms of diabetes.

Conclusion

Conclusion:

Glyburide will reduce the symptoms of type 2 diabetes by increasing the insulin level in the body.

(c)

Summary Introduction

To determine: The reason that glyburide can be used to treat type 1 diabetes with explanation.

Introduction:

Glyburide is an antidiabetic drug that has sulfonylureas that close relation with sulfonamide antibiotic. Type 1 diabetes is an autoimmune condition in which immune system immune system remain active.

Explanation of Solution

Explanation:

Type 1, diabetes is caused by the defect in pancreatic cells. The glyburide drug is not useful for the Type 1 diabetes patients, because glyburide act on pancreatic cell to produce insulin, which maintain the level of glucose in the body.

Conclusion

Conclusion:

Type 1 diabetes occurs due to the defect in pancreatic cell. Glyburide drug is not useful for its treatment.

(d)

Summary Introduction

To determine: The importance of iodinated glyburide that has same binding characteristic with unaltered glyburide.

Introduction:

Insulin is the peptide hormone that is secreted by pancreas; insulin is produced naturally in the body of organism. Insulin is required by the cells to use glucose as energy source. Glyburide is an antidiabetic drug that has sulfonylureas that close relation with sulfonamide antibiotics.

Explanation of Solution

Pictorial representation:

Fig1: Represent the Iodinated glyburide:

Explanation:

Glyburide show high affinity for SUR protein. Chlorine of glyburide is replaced by iodinated glyburide. Iodinated glyburide will not bind to SUR as glyburide does. If binding will not occur then wrong protein is cloned. This is required to differentiate iodinated glyburide with glyburide.

Conclusion

Conclusion:

Iodinated glyburide is required to differentiate iodinated glyburide with glyburide.

(e)

Summary Introduction

To determine: The reason for the requirement of antibody binding step.

Introduction:

Antibodies are also known as immunoglobulins, which are made up of proteins. These proteins will protect the living organism from the foreign substances. Glyburide is an antidiabetic drug that has sulfonylureas that close relation with sulfonamide antibiotics

Explanation of Solution

Explanation:

To purify the desired protein from a mixture of different proteins antibody-binding step is required. Antibody-binding step efficiently is used to separate desired protein from the mixture of different protein.

Conclusion

Conclusion:

Antibody binding step will separate out the desired protein from the mixture of different proteins.

(f)

Summary Introduction

To determine: The importance of putative SUR $\text{cDNA}-\text{mRNA}$ hybridization step.

Introduction:

Hybridization is the method that is used for the interbreeding of an individual from different population to produce hybrid. SUR subunit has 17 subunits that have 17 transmembrane domain.

Explanation of Solution

Explanation:

It is important to include putative SUR $\text{cDNA}-\text{mRNA}$ hybridization step because cloned genes may code same sequences in another protein. The $\text{mRNA}$ hybridization leads to distinct result with putative SUR gene which will encode actual SUR gene.

Conclusion

Conclusion:

Hybridization step is important because cloned genes may code same sequences in another protein.

(g)

Summary Introduction

To determine: The name of ${}^{125}\text{I}$-labeled140 $\text{kDa}$ protein that is found in experiment 2.

Introduction:

Gene cloning is the method by which similar copies of particular genes are produced. DNA cloning is a molecular technique that is used to make identical copies of the target gene.

Explanation of Solution

Explanation:

The following table represents the ${}^{125}\text{I}$-labeled 140 $\text{kDa}$:

Experiment	Cell type	Added Putative SUR $\text{cDNA}$	Added excess unlabeled glyburide	${}^{125}\text{I}$-labeled 140 $\text{kDa}$ protein.
1	HIT	No	No	+++
2	HIT	No	Yes	-
3		No	No	-
4		Yes	No	+++
5		Yes	Yes	-

From the given table, the ${}^{125}\text{I}$-labeled 140 $\text{kDa}$ is not present in the second experiment because of the presence of unlabelled glyburide, which will bind to the SUR gene. Hence,  less binding of unlabeled glyburide will result in less detection ${}^{125}\text{I}$-labeled 140 $\text{kDa}$.

Conclusion

Conclusion:

In the second experiment ${}^{125}\text{I}$-labeled 140 $\text{kDa}$ is not present due to high unlabelled glyburide.

(h)

Summary Introduction

To determine: The information from the given table to argue that $\text{cDNA}$ encode SUR.

Introduction:

Gene cloning is the method by which similar copies of particular genes are produced. DNA cloning is a molecular technique that is used to make identical copies of the target gene.

Explanation of Solution

Explanation:

The ${}^{125}\text{I}$-labeled 140 $\text{kDa}$ proteins are present in the absence of unlabeled glyburide and in the presence of putative SUR gene. Unlabelled glyburide will compete with labeled glyburide and ${}^{125}\text{I}$-labeled 140 $\text{kDa}$ proteins will not be detected. This will prove that the cloned gene encodes SUR protein which has similar weight as the SUR that is obtained from $\text{cDNA}$.

Conclusion

Conclusion:

The weight of cloned gene encodes SUR protein and weight as the SUR that is obtained from $\text{cDNA}$ is similar.

(i)

Summary Introduction

To enlist: The extra information that is required to prove that SUR gene is cloned.

Introduction:

Gene cloning is the method by which similar copies of particular genes are produced. DNA cloning is a molecular technique that is used to make identical copies of the target gene.

Explanation of Solution

Explanation:

To prove that SUR gene is cloned following information are required:

1) Check whether the transformed cells have ATP- gated ${\text{K}}^{\text{+}}$ channel activity.

2) ATP- gated ${\text{K}}^{\text{+}}$ channel must be deficient in mutation.

3) Check whether these organisms are able to produce insulin by introducing mutants of the putative SUR gene.

Conclusion

Conclusion:

To prove that SUR gene is cloned, ATP-gated ${\text{K}}^{\text{+}}$ channel activity must be checked.