Free calcium ions play pivotal role in signalling process in T-lymphocyte. There are variety of parameters exist in T-lymphocyte that affect the cytosolic calcium concentration. Protein plays important role in maintaining the free calcium ion concentration level in cytosol. In the present work, an attempt has been made to study the effect of protein on cytosolic calcium distribution in T-Lymphocyte. A mathematical model is developed in the form of reaction advection-diffusion equation. All-important parameters like protein concentration, diffusion coefficient, etc., have been incorporated in the mathematical model. Finite volume method is employed to obtain the solution. The obtained results are represented graphically with the help of MATLAB. The role of proteins is found significant to maintain the cytosolic calcium ions’ concentration. Any distribution in protein concentration leads to the cell death.