### PHKB Gene Overview

**Gene Symbol**: PHKB  
**Function**: The PHKB gene encodes the beta subunit of phosphorylase kinase, which plays a critical role in glucose metabolism by regulating glycogen breakdown. This enzyme is essential for the mobilization of glucose from glycogen stores in response to hormonal signals.

### 1. Associated Genes
While the summaries provided focus on the subunit composition of phosphorylase kinase, other genetic associations relevant to PHKB include:
- **PHKA1** and **PHKA2**: These genes code for the alpha subunits of phosphorylase kinase, which have skeletal and hepatic isoforms.
- **PHKG1** and **PHKG2**: These encode the gamma subunits and are involved in muscle and liver enzyme activity.
- **CALM1, CALM2, CALM3**: These genes encode calmodulin proteins, which function as the delta subunit of phosphorylase kinase.

### 2. Aging and Age-Related Diseases
Current research indicates that disruptions in glycogen metabolism, including deficiencies in phosphorylase kinase, can have implications for aging. Specifically, altered glucose homeostasis is associated with age-related diseases, including type 2 diabetes and other metabolic syndromes. Some studies suggest that impaired muscle glycogen metabolism might contribute to physical frailty in aging individuals. Additionally, as PHKB mutations are linked to glycogen storage diseases, it may be observed that age-related mechanisms of stress (like oxidative stress) can exacerbate symptoms of conditions arising from these genetic defects.

### 3. Drug Interactions
Currently, there are no specific drugs classified as targeting PHKB directly. However, pharmacological agents that influence glycogen metabolism, such as:
- **Glucagon**: This hormone promotes glycogen breakdown and may indirectly influence phosphorylase kinase activity.
- **Insulin**: While insulin promotes glucose storage in the form of glycogen, any drugs affecting insulin signaling can influence the regulatory mechanisms involving phosphorylase kinase.

### 4. Pathways and Biological Processes
PHKB has several key biological processes and pathways it is involved in, including:
- **Glycogen Metabolism**: Primarily through the phosphorylation of glycogen phosphorylase, leading to glycogen breakdown.
- **Calcium Signaling Pathway**: The delta subunit's regulation by calcium is significant for cellular signaling in response to various stimuli.
- **Signal Transduction**: It participates in endocrine signaling mechanisms, responding to hormonal changes such as those from glucagon and epinephrine.

Other pathways linked to PHKB include:
- **Regulation of glucose levels**: By affecting glycogenolysis.
- **Muscle contraction**: Due to its interaction with troponin I and influence on muscle energy metabolism.

Overall, PHKB plays a significant role in carbohydrate metabolism, has implications in glycogen storage diseases, and may be connected to broader metabolic pathways relevant to aging and cellular homeostasis.