The PAPPA2 gene (Pappalysin 2) is indeed an important gene within the pappalysin family, specializing in the modulation of the insulin-like growth factor (IGF) pathway. Below are additional details relevant to your inquiries:

### 1. Associated Genes
PAPPA2 is closely associated with several other genes, especially those involved in the IGF signaling pathway and proteolytic processes. Notably, it works in conjunction with:
- **IGFBP5**: The primary substrate for PAPPA2.
- **IGFBP3**: As mentioned, although PAPPA2 cleaves IGFBP5 specifically, it has limited proteolysis towards IGFBP3 as well.
- **PAPPA**: The paralog of PAPPA2, which shares similarities in function and structure.

### 2. Aging and Age-Related Diseases
There is increasing evidence linking PAPPA2 to aging and age-related conditions:
- **IGF Signaling**: The IGF pathway is central to growth and aging processes. PAPPA2's ability to cleave IGFBP5 enhances bioavailability of IGF, which is associated with various age-related diseases.
- **Obesity and Diabetes**: Variants in this gene have been explored in the context of metabolic syndromes including obesity and type 2 diabetes, wherein dysregulation of IGF signaling may play a crucial role.
- **Cardiovascular Diseases**: Some studies suggest a relationship between PAPPA2 activity and cardiovascular health, especially as they relate to age-related accumulation of atherosclerosis.
  
### 3. Drug Interactions
While no specific drugs are currently targeted specifically at PAPPA2, several drug classes may indirectly affect its activity through modulation of IGF signaling:
- **IGF-1 Inhibitors**: Compounds targeting the IGF pathway may alter the effects of PAPPA2 by changing IGF bioavailability.
- **Metalloproteinase Inhibitors**: General inhibitors of metalloproteinases can influence the function of all metzincins, including PAPPA2, although these are not specifically known to target it.
  
### 4. Pathways and Biological Processes
PAPPA2 is involved in numerous biological pathways and processes, including but not limited to:
- **Insulin-like Growth Factor (IGF) Signaling**: PAPPA2's primary role in the cleavage of IGFBP5 enhances IGF signaling.
- **Cell Growth and Proliferation**: It is intricately intertwined with processes that govern cellular growth dynamics.
- **Regulation of Proteolysis**: As a metalloproteinase, PAPPA2's function contributes to the broader family of extracellular matrix remodeling and proteolytic activity.
- **Developmental Processes**: Involved in developmental biology, particularly in processes that require precise modulation of IGF signaling for proper growth and development.

In summary, PAPPA2 is a significant gene that links various biological mechanisms, particularly related to growth, aging, and metabolism. Further research may continue to elucidate its relevance in human health and disease.