Capsid protein that self-associates to form 11 pentons, building the T=13 laevo capsid in association with 160 hexamers of gp23* and one dodecamer of gp20. Homopentamer. A total of 55 subunits of gp24 forms the 11 pentamers. Interacts with portal protein gp20. Interacts with gp23 that forms 160 hexamers. Proteolytic cleavage give rise to gp24*. Belongs to the T4 phage capsid protein family.