Molecular characterization and expression of equine testicular cytochrome P450 aromatase.

The researchers have studied and described the equine (horse) testicular aromatase, a protein involved in hormone conversion, and how it is expressed.

Study of Equine Testicular Aromatase

The team of researchers isolated a sequence of the horse’s DNA, specifically the cDNA molecule that is 2707 base pairs long. This segment of DNA contains the instructions to create a protein known as equine testicular cytochrome P450 aromatase.

• The team discovered that within this segment, the information, also referred to as codons, to make a chain of 503 amino acids is encoded.
• This chain of amino acids folds to create a polypeptide, the functional unit of the protein.
• After analysing the properties of the polypeptide, it was determined that the molecular mass of the resulting protein is 57.8 kilodaltons (kDa).

Comparison to Human Counterpart

The researchers compared the equine aromatase to the corresponding human aromatase to spot any similarities or differences. This comparison revealed that the horse’s protein shares 78% of its structure with the human one, highlighting their significant similarity.

Expression and Structure of the Aromatase Gene

By studying the full length of the gene responsible for making this protein, the researchers found that it is at least 74 kilobases long and consists of 9 separate sections (exons) that are involved in coding the protein. The gene was found to express an RNA molecule that is 2.8 kilobases in length in the horse testis. This RNA acts as a template for the assembly of the aromatase protein.

Evaluation of Aromatase Activation and Forms

The researchers also studied the activation of the aromatase protein and its different forms.

• They executed transfections of cDNA in E293 cells and in vitro translations in a reticulocyte lysate system to detect the presence and activity of the aromatase protein.
• The researchers found that the activity of the protein increased in a dose-dependent manner when a steroid hormone precursor known as androstenedione was present as a substrate.
• By isolating the aromatase via a new type of purification method (immunoaffinity), the team noticed that the protein can exist in two different forms, a glycosylated form and a non-glycosylated form, with a noticeable difference in weight of about 2 kDa.

Implications of the Study

The results from this study pave the way for novel structural studies of this type of aromatase, potentially significantly advancing our understanding of the molecular mechanisms of this protein and its role in steroid hormone synthesis.