Protein sequences in one organism that resemble those of another suggest a

shared ancestry

Explanation:

Sequences of proteins in one organism that resemble those of another suggest that these organisms have a shared ancestry, that is, they have the same ancestor in common.

A common ancestor is an organism that was alive for centuries ago and through a continuous process of evolution gave rise to other populations of living beings that share physical and genetic similarities.

Shared a common ancestry

Explanation:

All life on earth have been evolved from a single cell organism lived nearly 3.5 billion years ago. Universal common ancestor theory proposed by Darwin nearly 150 years. According to Douglas Theobald a biochemist reported that the probability between a human DNA polymerase and another protein with an E. coli are much higher. because human and E. coli are related to each other.