calcium pump. the mechanism of active transport of calcium (Ca 2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.
A rental agreement differs from a lease agreement in that it is not a long-term contract and usually occurs on a month-to-month basis. This month-to-month lease agreement expires and then renews each month upon agreement of the parties involved.
The lease is a contract in which: 1  You agree to pay rent for a certain period of time. 2  You agree to abide by other conditions (such as using the space for a consulting business only, or not displaying outside signs unless the landlord first approves them).