Category: Lab Notes

RNF115 (BCA2) is a dual RING/U‑box E3 ubiquitin ligase that regulates membrane trafficking, innate immunity and antiviral defence. By ubiquitinating BST‑2/Tetherin, Rab7‑associated endosomal proteins and EGFR, RNF115 influences receptor turnover, immune signalling and cancer progression, making it a key regulator of cellular homeostasis.

U‑box ubiquitin ligases are RING‑type E3 enzymes with a modified U‑box domain that enables zinc‑independent ubiquitin transfer. Key members such as CHIP, PRPF19 and UBOX5 regulate chaperone‑mediated protein quality control, DNA‑damage repair and cellular stress responses, making the U‑box family essential for proteostasis and genome stability.

RBR ubiquitin ligases are hybrid E3 enzymes that combine RING‑type E2 binding with HECT‑like catalytic ubiquitin transfer. Through key members such as Parkin, HHARI and HOIP, the RBR family regulates mitophagy, protein‑quality control and M1‑linked ubiquitination in immune signalling, making them central to cellular stress responses and disease mechanisms.

HECT ubiquitin ligases are catalytic E3 enzymes that form a thioester intermediate with ubiquitin, allowing precise control of ubiquitin‑chain architecture. Through NEDD4‑family ligases, HERC proteins and HUWE1, the HECT class regulates receptor endocytosis, DNA‑damage signalling, proteostasis and diverse cellular stress responses.

Non‑obstructive azoospermia is a severe form of male infertility caused by failure of spermatogenesis. Genetic defects, Y‑chromosome microdeletions, meiotic‑gene mutations and hormonal disorders lead to complete absence of sperm in the ejaculate. Understanding NOA is essential for diagnosis, genetic counselling and identifying candidates for micro‑TESE and assisted reproduction.

K48‑linked ubiquitination is the principal degradation signal in eukaryotic cells, directing proteins to the 26S proteasome. Built by E1, E2 and E3 enzymes, K48‑linked chains regulate protein turnover, cell‑cycle progression and DNA‑damage responses, forming a central mechanism for maintaining proteostasis and preventing toxic protein accumulation.

Premature ageing describes the accelerated decline of cellular and physiological functions caused by genomic instability, telomere attrition, mitochondrial dysfunction and chronic inflammation. These processes activate ageing pathways earlier than expected, leading to early onset of tissue deterioration, reduced homeostasis and increased vulnerability to age‑related diseases.

Ageing is a gradual biological process driven by genomic instability, telomere shortening, mitochondrial dysfunction and cellular senescence. These changes reduce physiological resilience, impair tissue repair and increase susceptibility to chronic disease. Understanding the mechanisms of ageing provides insight into longevity, healthspan and the development of age‑related disorders.

Metabolic disorders occur when biochemical pathways responsible for processing nutrients and generating energy become disrupted. These conditions may involve defects in glycolysis, fatty‑acid oxidation, mitochondrial function or endocrine signalling. Their consequences range from mild metabolic imbalance to severe systemic disease, affecting growth, neurological function and long‑term health.

Nutrient deprivation creates metabolic stress that suppresses mTOR, activates AMPK and induces autophagy. These pathways help cells conserve energy, recycle intracellular components and maintain homeostasis during starvation or limited nutrient availability. Prolonged nutrient deprivation influences gene expression, stress signalling and survival mechanisms across diverse cell types.

Hydrolytic enzymes catalyse the breakdown of macromolecules by adding water to chemical bonds. Found in lysosomes, digestive organs and immune cells, they degrade proteins, nucleic acids, lipids and carbohydrates. Their activity maintains cellular homeostasis, supports nutrient acquisition and protects against pathogens, while dysregulation contributes to metabolic and degenerative diseases.

Autophagosomes are double‑membrane vesicles that capture cytoplasmic material for lysosomal degradation. Formed from expanding phagophores and marked by LC3 lipidation, autophagosomes are central to autophagy, enabling cells to recycle nutrients, remove damaged organelles and maintain homeostasis. Their dysfunction contributes to neurodegenerative, metabolic and cancerous diseases.

Limb development is the process that builds vertebrate appendages through coordinated signalling, patterning, and morphogenesis. This article explains the roles of the AER, ZPA, and key molecular pathways.

Vertebral column formation is the process that builds the axial skeleton from somites. This article explains resegmentation, sclerotome differentiation, Hox patterning, and endochondral ossification.

Cdh1 is a major activator of the APC/C complex, responsible for mitotic exit, G1 maintenance and replication licensing. By degrading Cyclin B, Aurora A, Plk1 and Geminin, Cdh1 prevents premature S‑phase entry and maintains genomic stability. Its dysregulation contributes to replication stress, chromosomal instability and cancer development.