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.
Standard rental agreements are month-to-month, and there is no set period of residence. Both the landlord and tenant are free at the end of each 30-day period to make changes to the rental agreement, subject to any rent control laws.