Abstract: In sealing body (6) of a tube lamp which seals side tube (3) which is connected to arc tube (2) and which securely holds upholding parts (7) of the electrodes by a shrink seal and which consists of a functional gradient material, in which an electrically conductive component and a dielectric component in the axial direction of the tube have a continuous or gradual concentration gradient, and in which one side is dielectric and the other side is electrically conductive, the object of the invention is achieved by upholding parts (7) of the electrodes being located in an opening of this functional gradient material without a gap in a shrink seal, and by the surface of the area of upholding parts (7) of the electrodes which are located in the opening of the functional gradient material being coated at least partially with thin layer (9) of a metal with a high melting point.